JWT explained: how to decode tokens safely
Learn JSON Web Token structure, common claims, and why decoding is not the same as verification.
2026-06-01 · 6 min read
Guides
Original tutorials and reference articles for developers and automation engineers. Each guide links to related Flashman tools you can use immediately in your browser.
255 guides · also read our blog
JSON formatting and validation: a practical guide
How to pretty-print, minify, and validate JSON for APIs, configs, and logs—without leaking data.
2026-06-01 · 5 min read
Base64 encoding explained (and why it is not encryption)
What Base64 is for, when to use it, and common pitfalls with Unicode and padding.
2026-05-28 · 4 min read
YAML vs JSON: when to use each format
Compare readability, tooling, and trade-offs for configuration and APIs.
2026-05-28 · 5 min read
Cron expressions: schedule jobs with confidence
Understand five-field cron syntax and avoid timezone surprises in production.
2026-05-25 · 5 min read
URL encoding: common mistakes and fixes
Percent-encoding rules for query strings, paths, and plus signs in form data.
2026-05-25 · 4 min read
Why client-side developer tools protect your data
How in-browser processing reduces leak risk for tokens, configs, and customer data.
2026-05-20 · 4 min read
MATLAB & Simulink: JSON workflows for engineers
Bridge JSON configuration and MATLAB matrices or structs for automation and calibration.
2026-05-20 · 6 min read
SHA hashing explained for developers
What SHA-256 and SHA-512 do, when to use them, and what hashing is not.
2026-05-18 · 4 min read
Markdown writing guide: syntax, preview, and export
Learn Markdown basics — headings, lists, code blocks, tables — and how to preview or export to PDF in your browser.
2026-06-02 · 7 min read
Regex testing workflow: match with confidence
How to prototype regular expressions safely before shipping validation logic.
2026-05-18 · 5 min read
Portainer stack environment variables: a safe deploy guide
Prepare Portainer stack variables, Docker Compose references, secrets, domains, ports, and rollback notes before updating self-hosted services.
2026-07-23 · 7 min read
API payload debugging checklist for production incidents
A practical checklist for inspecting API payloads, encoded fields, tokens, and diffs during production debugging.
2026-07-09 · 7 min read
QR codes for developers: URLs, Wi-Fi, and vCard
When to use QR codes, what to encode, and how to generate them safely for apps and documentation.
2026-06-03 · 5 min read
Hex, RGB, and contrast: a color guide for UI work
Convert between color formats, check contrast, and avoid common mistakes in design systems.
2026-06-03 · 6 min read
UUIDs and correlation IDs in distributed systems
Generate UUID v4 values, trace requests across services, and avoid ID collisions.
2026-06-04 · 5 min read
Password generators: length, entropy, and storage
Create strong passwords in the browser and learn why generation is only half the problem.
2026-06-04 · 5 min read
Unix timestamps and ISO dates: conversion guide
Convert epoch seconds, milliseconds, and ISO-8601 strings without timezone bugs.
2026-06-05 · 5 min read
Text and JSON diff: compare changes with confidence
Side-by-side diffs for configs, API payloads, and code review prep.
2026-06-05 · 5 min read
XML formatting and minification for configs and APIs
Pretty-print XML, validate structure, and ship readable configs to operations teams.
2026-06-06 · 5 min read
SQL formatting for readable queries and code review
Indent SELECT statements, align JOINs, and share queries your team can maintain.
2026-06-06 · 4 min read
CSS beautify and minify for production bundles
Format messy CSS for debugging and minify for faster page loads.
2026-06-07 · 4 min read
HTML entities: encode text for safe markup
Escape &, <, >, and quotes to prevent XSS and fix broken HTML snippets.
2026-06-07 · 4 min read
camelCase, snake_case, and kebab-case: naming guide
Convert identifiers between conventions for JSON, APIs, CSS, and databases.
2026-06-08 · 4 min read
Binary, octal, decimal, and hex conversion
Convert between number bases for low-level debugging, flags, and hardware docs.
2026-06-08 · 5 min read
JSON API type contracts: numbers, strings, nulls, and IDs
Design and debug stable JSON API types across schemas, serializers, databases, generated clients, and production payloads.
2026-08-26 · 8 min read
JWT client identity claims: aud, azp, client_id, and sub
Map JWT identity claims to OAuth clients, resource servers, users, and gateway authorization rules without weakening token verification.
2026-08-26 · 8 min read
Cron calendar semantics across Linux, Kubernetes, and cloud schedulers
Understand cron day-field logic, dialect differences, timezones, daylight saving, retries, and idempotency before scheduling production jobs.
2026-08-26 · 8 min read
Base64 across MIME, JSON, URLs, and environment variables
Move Base64 data safely across transport boundaries by handling alphabets, padding, line wrapping, escaping, size, and byte-level checks.
2026-08-26 · 8 min read
Regex performance and ReDoS safety guide
Design, test, and bound regular expressions so ambiguous backtracking on untrusted input does not become a production performance incident.
2026-08-26 · 8 min read
JSON Patch concurrency: indexes, identities, and safe updates
Design reliable JSON Patch APIs with stable identities, conditional requests, ordered operations, conflict handling, and regression fixtures.
2026-08-27 · 8 min read
OAuth certificate-bound tokens and JWT cnf claims
Implement and debug certificate-bound access tokens across OAuth servers, mTLS gateways, JWT validation, certificate rotation, and trusted proxy hops.
2026-08-27 · 8 min read
Scheduler clock corrections, duplicate runs, and idempotency
Operate scheduled jobs safely through NTP steps, VM resumes, clock jumps, failover, retries, and duplicate dispatches with durable execution keys.
2026-08-27 · 8 min read
Binary-safe Base64: bytes, Unicode, and round-trip validation
Preserve arbitrary binary bytes through Base64 workflows by separating text encoding from file data, checking hashes, limiting size, and testing round trips.
2026-08-27 · 8 min read
YAML schema type safety across CI and application parsers
Prevent YAML implicit-type bugs by understanding schemas, quoting ambiguous strings, comparing parsed JSON, and testing CI and application parser behavior.
2026-08-27 · 8 min read
SQL NULL and three-valued logic in production queries
Write reliable SQL around NULL with explicit predicates, safe joins, predictable anti-joins, typed parameters, and representative database fixtures.
2026-08-28 · 8 min read
Signed URL canonicalization and verification guide
Build and debug signed URLs with deterministic paths, query ordering, percent-encoding, duplicate parameters, expiry checks, and reusable test vectors.
2026-08-28 · 8 min read
HTML output encoding by context without double-escaping
Prevent XSS and visible entity bugs by separating canonical text, HTML encoding, URL validation, DOM sinks, rich-text sanitization, and regression tests.
2026-08-28 · 8 min read
CSS custom properties, fallbacks, and cascade layers
Design resilient CSS tokens by understanding computed values, inheritance, fallback semantics, layer order, themes, typed properties, and browser diagnostics.
2026-08-28 · 8 min read
Portable Markdown code fences and nested examples
Write nested Markdown examples that survive CommonMark, GFM, documentation generators, syntax highlighting, sanitization, and PDF export.
2026-08-28 · 8 min read
XML namespaces and SOAP integration guide
Build reliable XML integrations by understanding expanded names, default namespaces, XPath bindings, SOAP versions, schema validation, and safe test fixtures.
2026-08-29 · 8 min read
Timestamp instants, offsets, and safe API round trips
Design time-safe APIs by separating instants, local times, dates, offsets, zones, epoch units, precision, storage behavior, and browser presentation.
2026-08-29 · 8 min read
UUID contracts across APIs and databases
Use UUIDs consistently across text, JSON, binary storage, database drivers, validation, indexing, logging, authorization, and version-aware application contracts.
2026-08-29 · 8 min read
YAML multiline scalars and exact whitespace
Control YAML multiline strings with literal and folded styles, indentation, chomping, line endings, interpolation boundaries, and byte-aware deployment tests.
2026-08-29 · 8 min read
Reliable QR codes for URLs and mobile deep links
Ship dependable QR flows by designing safe URLs, encoding components, controlling payload density, testing physical output, handling app routing, and providing fallbacks.
2026-08-29 · 8 min read
JSON Merge Patch API design and safe partial updates
Design predictable JSON Merge Patch endpoints with explicit null semantics, stable object contracts, concurrency controls, validation, authorization, and test fixtures.
2026-08-30 · 8 min read
Nested JWT validation with typ and cty headers
Validate nested JWTs safely by defining token profiles, processing encryption and signatures in order, constraining algorithms, and assigning claims to trust boundaries.
2026-08-30 · 8 min read
Base64 API size budgets and memory-safe transport
Set reliable Base64 payload budgets by calculating expansion, including JSON and protocol overhead, enforcing decoded limits, choosing streaming transports, and testing gateways.
2026-08-30 · 8 min read
Scheduled job jitter, capacity, and thundering herd control
Design scheduled workloads that avoid synchronized spikes with deterministic jitter, queues, concurrency limits, idempotency, deadlines, backpressure, and capacity tests.
2026-08-30 · 8 min read
Unicode-safe regex and normalization guide
Build Unicode-aware text matching by separating code units, code points, grapheme clusters, normalization, locale rules, security boundaries, and runtime regex support.
2026-08-30 · 8 min read
JSON depth limits and safe complexity budgets
Protect JSON APIs from deeply nested input by measuring structural complexity, bounding parsers and validators, replacing unsafe recursion, and testing clear limits.
2026-08-31 · 8 min read
JWT x5c certificate chains and trust validation
Validate JWT x5c headers safely by separating token signatures from PKI trust, building certificate paths, constraining key use, and planning rollover.
2026-08-31 · 8 min read
Canonical Base64 encoding and strict decoding
Define interoperable Base64 boundaries with explicit alphabets, padding and whitespace rules, zero pad bits, canonical re-encoding, and signature-safe handling.
2026-08-31 · 8 min read
Cron calendar edge cases for month-end and leap years
Design reliable calendar schedules across short months, leap years, business-day rules, timezones, missed dates, retries, and next-run monitoring.
2026-08-31 · 8 min read
Safe SQL parameter binding across drivers
Build portable parameterized SQL by understanding driver placeholders, binding order, data types, collection expansion, prepared statements, and safe diagnostics.
2026-08-31 · 8 min read
Safe JSON object mapping and prototype pollution prevention
Map untrusted JSON safely with explicit schemas, controlled object construction, secure merge behavior, authorization boundaries, dependency updates, and regression tests.
2026-09-01 · 8 min read
OAuth DPoP proof validation and proxy-safe deployment
Validate OAuth DPoP proofs with constrained JWT algorithms, request binding, nonce handling, replay prevention, key thumbprints, trusted proxies, and clear diagnostics.
2026-09-01 · 8 min read
CSS stacking contexts, z-index, and reliable overlay layers
Design reliable CSS overlay layers by understanding stacking contexts, paint order, clipping, portals, the browser top layer, accessibility, and responsive tests.
2026-09-01 · 8 min read
XML CDATA, character data, and serializer-safe text
Handle XML text safely by choosing escaped character data or CDATA deliberately, splitting terminators, preserving encodings, using serializers, and testing signatures.
2026-09-01 · 8 min read
Portable Markdown links, images, and document assets
Build portable Markdown documents by choosing stable relative paths, encoded URLs, renderer-compatible anchors, packaged assets, accessible text, and link checks.
2026-09-01 · 8 min read
Exact integers in JSON API contracts
Preserve exact JSON integers by defining string and numeric contracts, tracing parser limits, selecting safe database types, and testing cross-runtime round trips.
2026-09-02 · 8 min read
Portable regex replacement and capture groups
Design reliable regex replacements by separating pattern and replacement grammars, using stable captures, controlling escape layers, and testing engine differences.
2026-09-02 · 8 min read
XML byte encodings, declarations, and parser boundaries
Process XML bytes reliably by reconciling declarations, BOMs, transport charsets, Unicode decoding, parser security, signatures, and round-trip fixtures.
2026-09-02 · 8 min read
CSS dimensions in calc and custom properties
Build dependable CSS calculations by defining token dimensions, composing compatible units, handling var fallbacks, tracing the cascade, and testing layouts.
2026-09-02 · 8 min read
URL path decoding across proxies and routers
Design unambiguous URL paths by controlling percent-decoding, separator handling, proxy normalization, canonicalization, authorization, caches, and signatures.
2026-09-02 · 8 min read
HTTP content encoding and safe decompression
Handle compressed HTTP responses safely by separating content coding from transfer framing, enforcing limits, preserving metadata, and testing every proxy boundary.
2026-09-03 · 8 min read
SQL deadlocks, transactions, and safe retries
Design database transactions that reduce deadlocks with stable lock ordering, useful indexes, bounded retries, idempotent effects, observability, and concurrency tests.
2026-09-03 · 8 min read
QR code print and scanning reliability
Create dependable printed QR codes by controlling payload density, quiet zones, module dimensions, contrast, error correction, export quality, and device testing.
2026-09-03 · 8 min read
Cross-platform text files and stable checksums
Create reliable text checksums by defining exact bytes, encodings, line endings, terminal newlines, canonical forms, artifact boundaries, and cross-platform tests.
2026-09-03 · 8 min read
Alpha colors and accessible contrast
Evaluate accessible contrast for transparent CSS colors by compositing real backgrounds, tracing opacity and blending, testing states, and validating rendered themes.
2026-09-03 · 8 min read
HTTP cache validators, ETags, and conditional requests
Design reliable HTTP revalidation with ETags, modification dates, cache keys, 304 responses, representation variants, proxies, and observable test cases.
2026-09-04 · 8 min read
Strict JSON processing for JWT headers and claims
Harden JWT processing by rejecting duplicate JSON names, constraining algorithms, preserving signed segments, validating claim types, and testing parser boundaries.
2026-09-04 · 8 min read
YAML alias expansion and parser resource safety
Process YAML safely with explicit byte, depth, alias, expansion, tag, time, and memory limits while reviewing effective configuration and parser upgrades.
2026-09-04 · 8 min read
Stable SQL pagination with offsets and keysets
Design predictable SQL pagination with total ordering, compound cursors, correct predicates, useful indexes, snapshot boundaries, and concurrent-write tests.
2026-09-04 · 8 min read
Password Unicode, byte limits, and safe hashing boundaries
Handle passwords safely across Unicode input, UTF-8 byte limits, normalization policy, hashing-library constraints, migrations, and non-secret test fixtures.
2026-09-04 · 8 min read
JSON contracts for NaN, Infinity, and invalid numbers
Design portable JSON number contracts by detecting non-finite calculations, choosing explicit domain representations, validating schemas, and testing language boundaries.
2026-09-05 · 8 min read
PEM key containers: PKCS#1, PKCS#8, and public keys
Handle PEM keys safely by identifying PKCS#1, PKCS#8, SubjectPublicKeyInfo, certificates, encryption, algorithms, line endings, and deployment boundaries.
2026-09-05 · 8 min read
Portainer and Docker Compose variable precedence
Deploy predictable stacks by separating Compose interpolation, container environment precedence, build arguments, Portainer values, secrets, and recreation behavior.
2026-09-05 · 8 min read
HMAC verification across hex, Base64, and raw bytes
Implement reliable HMAC verification by defining exact message and key bytes, digest algorithms, output encodings, replay controls, constant-time comparison, and tests.
2026-09-05 · 8 min read
IPv6 URL authorities, brackets, ports, and safe parsing
Handle IPv6 URLs correctly by parsing bracketed host literals, ports, canonical forms, zone identifiers, proxies, allowlists, signed requests, and test fixtures.
2026-09-05 · 8 min read
Multipart filenames, upload parsing, and safe storage
Handle multipart uploads safely by parsing boundaries and filename parameters, validating bytes, separating display names from storage keys, and testing clients.
2026-09-06 · 8 min read
JWT audience validation across gateways and APIs
Validate JWT audiences safely by handling string and array claims, requiring exact recipient identifiers, aligning gateway profiles, and testing trust boundaries.
2026-09-06 · 8 min read
Idempotent SQL migrations and interrupted deploy recovery
Design recoverable SQL migrations with explicit transactions, postcondition checks, restartable backfills, locking plans, compatibility windows, and rehearsed repairs.
2026-09-06 · 8 min read
Scheduler misfires, catch-up windows, and safe backfills
Choose safe missed-run behavior by defining catch-up windows, deadlines, idempotency, ordering, concurrency, outage capacity, observability, and backfill controls.
2026-09-06 · 8 min read
Two's complement, bit width, and signed integer boundaries
Interpret signed integers correctly by defining bit width, two's complement ranges, sign extension, byte order, overflow behavior, transport types, and fixtures.
2026-09-06 · 8 min read
CORS preflight policy, caching, and proxy behavior
Design CORS preflight handling with exact origin policy, method and header validation, credential rules, cache bounds, proxy behavior, and browser tests.
2026-09-07 · 8 min read
Content Security Policy deployment with nonces and hashes
Deploy Content Security Policy safely with directive fallbacks, per-response nonces or hashes, report collection, third-party inventories, and rollout tests.
2026-09-07 · 8 min read
WebSocket handshakes, proxies, and connection lifecycle
Operate reliable WebSockets through browsers, proxies, and load balancers with correct handshakes, origin policy, timeouts, heartbeats, close codes, and tests.
2026-09-07 · 8 min read
Secure XML entity processing and resource limits
Parse untrusted XML safely by controlling DTDs and entity resolution, bounding expansion and document work, isolating parsers, and validating effective data.
2026-09-07 · 8 min read
Timestamp precision across APIs, runtimes, and databases
Preserve timestamp precision across JSON, runtimes, and databases by defining units, fractional digits, rounding rules, storage types, and round-trip tests.
2026-09-07 · 8 min read
Designing reliable JSON Schema composition
Design predictable JSON Schema variants with oneOf, anyOf, allOf, explicit tags, non-overlapping branches, draft-aware validators, and contract fixtures.
2026-09-08 · 8 min read
Bearer token handling across proxy boundaries
Carry Bearer authentication safely across browsers, redirects, proxies, and services with explicit trust ownership, bounded headers, redacted logs, and tests.
2026-09-08 · 8 min read
Streaming Base64 without corrupting byte boundaries
Stream Base64 safely by carrying incomplete byte groups, separating transport chunks from messages, bounding memory, and verifying exact byte round trips.
2026-09-08 · 8 min read
SQL temporal types and timezone-safe data contracts
Model SQL dates, local times, and instants safely by defining temporal meaning, session zones, driver mappings, DST policy, precision, and round-trip tests.
2026-09-08 · 8 min read
Container query architecture for reusable components
Build container-query components with explicit boundaries, named containers, stable sizing, cascade-aware styles, progressive fallbacks, and layout tests.
2026-09-08 · 8 min read
Canonical JSON for deterministic signatures and hashes
Create deterministic signed JSON with a defined canonicalization profile, exact byte encoding, safe numeric constraints, verification order, and fixtures.
2026-09-08 · 8 min read
JWT delegation and OAuth token exchange boundaries
Model delegated authorization safely with explicit subject and actor identities, constrained token exchange, audience validation, audit data, and revocation.
2026-09-08 · 8 min read
Compressed Base64 payloads, expansion limits, and integrity
Process compressed Base64 safely by defining transform order and formats, enforcing limits at every expansion stage, streaming output, and testing bytes.
2026-09-08 · 8 min read
SQL upserts under concurrency and retry
Design reliable SQL upserts with correct conflict identity, atomic conditional updates, engine-specific semantics, bounded retries, observability, and tests.
2026-09-08 · 8 min read
CSS logical properties for RTL and writing modes
Build adaptable layouts with logical dimensions, spacing, borders, and positioning while controlling direction, icon mirroring, cascade fallbacks, and tests.
2026-09-08 · 8 min read
OAuth PKCE verifier generation, storage, and validation
Implement OAuth PKCE safely with high-entropy verifiers, exact S256 encoding, transaction-bound storage, one-time callbacks, and production test fixtures.
2026-09-09 · 8 min read
YAML duplicate keys, merges, and effective configuration
Prevent YAML configuration ambiguity by rejecting duplicate keys, controlling merges and templates, validating effective output, and aligning every parser.
2026-09-09 · 8 min read
SQL write skew, invariants, and serializable transactions
Protect cross-row database invariants by recognizing write skew, selecting constraints or coordination locks, using serializable retries, and testing concurrency.
2026-09-09 · 8 min read
UUIDv7 ordering, storage, and distributed generation
Use UUIDv7 safely by understanding timestamp fields, monotonic generation limits, byte ordering, trust boundaries, pagination ties, and clock rollback.
2026-09-09 · 8 min read
SameSite cookies for redirects, embeds, and API requests
Design reliable browser sessions by classifying same-site contexts, selecting cookie attributes, protecting cross-site flows, tracing proxies, and testing browsers.
2026-09-09 · 8 min read
JSON Unicode scalar values and lone surrogate handling
Build interoperable JSON boundaries by distinguishing code units from scalar values, rejecting lone surrogates, preserving bytes, and testing every runtime.
2026-09-10 · 8 min read
SQL version columns for optimistic concurrency control
Prevent lost updates with atomic version predicates, explicit conflict semantics, bounded retries, complete write-path coverage, observability, and race tests.
2026-09-10 · 8 min read
IDNA, Punycode, and internationalized URL hostnames
Process internationalized hostnames safely by parsing URL boundaries, applying a defined IDNA profile, comparing A-labels, and testing DNS and TLS behavior.
2026-09-10 · 8 min read
XML signature wrapping defense through verified node binding
Defend XML signature consumers by constraining references, enforcing unique IDs and schema, binding business logic to verified nodes, and testing wrapping attacks.
2026-09-10 · 8 min read
CSS OKLCH gamut mapping, fallbacks, and contrast
Ship robust OKLCH color systems by managing gamut boundaries, generated fallbacks, browser conversion, contrast, themes, exports, and visual regression tests.
2026-09-10 · 8 min read
HTTP empty responses and reliable JSON client decoding
Build API clients by separating HTTP status semantics from JSON decoding, modeling no-content results, preserving errors, and testing response boundaries.
2026-09-11 · 8 min read
JWT scope claims and exact authorization matching
Design JWT authorization by defining scope claim types, validating token profiles, matching permissions, separating roles, and aligning gateways with APIs.
2026-09-11 · 8 min read
SQL decimal precision, scale, and money calculations
Keep money exact across APIs and SQL by defining decimal precision, scale, rounding, driver bindings, aggregates, serialization, and regression tests.
2026-09-11 · 8 min read
Scheduled job timeouts, cancellation, and process cleanup
Operate scheduled jobs by propagating cancellation, managing process trees and leases, bounding remote calls, reconciling side effects, and testing shutdown.
2026-09-11 · 8 min read
Portable Markdown front matter and metadata schemas
Create portable Markdown metadata by controlling delimiters, YAML types, encodings, field schemas, dates, validation, migrations, and safe preview workflows.
2026-09-11 · 8 min read
HTTP redirect methods, request replay, and credential safety
Design reliable HTTP redirects by selecting status semantics, controlling method and body replay, protecting credentials, managing caches, and testing real clients.
2026-09-12 · 8 min read
JWT jti replay prevention and cache design
Implement JWT replay controls by defining one-time token profiles, validating trusted context, performing atomic first-use checks, retaining IDs, and handling outages.
2026-09-12 · 8 min read
SQL collation and case-insensitive identity constraints
Enforce reliable text identity by defining equivalence, selecting SQL collations or normalized keys, handling Unicode, constraining concurrency, and migrating safely.
2026-09-12 · 8 min read
Regex empty matches and safe global iteration
Build terminating regex loops by understanding zero-width assertions, empty alternatives, runtime iteration rules, Unicode offsets, replacements, and resource limits.
2026-09-12 · 8 min read
XML mixed content, whitespace, and safe serialization
Preserve XML meaning by classifying mixed content, respecting xml:space and grammar rules, separating pretty views from source, and testing serializers and signatures.
2026-09-12 · 8 min read
NDJSON streaming parsers, boundaries, and recovery
Build reliable NDJSON pipelines by separating chunks from records, decoding UTF-8 incrementally, bounding buffers, handling EOF, and reporting errors safely.
2026-09-13 · 8 min read
SQL savepoints and safe partial transaction recovery
Use SQL savepoints safely by modeling nested work, engine error states, deferred constraints, lock behavior, external effects, retries, and commit outcomes.
2026-09-13 · 8 min read
YAML multi-document streams and parser contracts
Process YAML streams predictably by defining document counts, separators, directives, empty values, schema validation, resource limits, and conversion rules.
2026-09-13 · 8 min read
JWS unencoded and detached payload verification
Implement RFC 7797 JWS profiles with protected b64 and crit headers, exact payload bytes, constrained serialization, trusted key policy, and conformance tests.
2026-09-13 · 8 min read
Markdown reference links, autolinks, and safe rendering
Publish reliable Markdown links by defining parser extensions, label resolution, destination escaping, URL safety policy, HTML sanitization, and tests.
2026-09-13 · 8 min read
JSON Pointer reference tokens, fragments, and patches
Use JSON Pointer safely by encoding slash and tilde tokens correctly, separating URI fragments, handling arrays, and evaluating JSON Patch operations in order.
2026-09-13 · 8 min read
JOSE ECDSA signature formats and validation
Implement ES256 and related JWS algorithms by converting DER and JOSE signatures correctly, enforcing fixed widths, preserving signing bytes, and constraining keys.
2026-09-13 · 8 min read
SQL advisory locks with transactions and pools
Use database advisory locks safely by defining stable keys, choosing session or transaction ownership, controlling pooled connections, and testing failure cleanup.
2026-09-13 · 8 min read
HTTP Structured Fields parsing and serialization
Process HTTP Structured Fields reliably by selecting the declared data type, parsing parameters and inner lists, preserving semantics, and testing intermediaries.
2026-09-13 · 8 min read
Distributed scheduler leadership and failover safety
Design resilient scheduled jobs with occurrence identities, leased leadership, fencing, durable dispatch claims, idempotent effects, and controlled failover tests.
2026-09-13 · 8 min read
HTTP byte ranges and reliable resumable downloads
Implement resumable downloads with correct byte intervals, Content-Range responses, representation validators, encoding rules, cache behavior, and integrity checks.
2026-09-17 · 8 min read
JSON Schema unevaluated properties and composition
Close composed JSON object schemas predictably by understanding evaluated properties, dialects, references, conditional branches, extension points, and validator tests.
2026-09-17 · 8 min read
SQL SKIP LOCKED work queues without starvation
Build database-backed worker queues with short row locks, durable claims, stable ordering, leases, fencing, fair retries, idempotent effects, and failure recovery.
2026-09-17 · 8 min read
Idempotent webhook inboxes, retries, and ordering
Process at-least-once webhooks with exact-byte verification, durable event claims, ordered state changes, prompt acknowledgements, replay controls, and safe retries.
2026-09-17 · 8 min read
Stable Markdown heading anchors across renderers
Keep Markdown table-of-contents and deep links reliable by controlling heading slug generation, duplicate IDs, Unicode, explicit anchors, sanitization, and link checks.
2026-09-17 · 8 min read
HTTP Expect and 100 Continue for reliable uploads
Design large-upload paths with explicit Expect handling, interim responses, early rejection, bounded timeouts, proxy behavior, body limits, retries, and diagnostics.
2026-09-18 · 8 min read
HTTP early data, 425 responses, and replay safety
Use TLS early data only on replay-safe operations by classifying endpoint effects, handling 425 fallback, propagating edge context, and testing idempotency.
2026-09-18 · 8 min read
Problem Details contracts for HTTP APIs
Design consistent application/problem+json errors with stable type identifiers, safe extensions, gateway coverage, localization, observability, and client fallbacks.
2026-09-18 · 8 min read
PostgreSQL ON CONFLICT with partial unique indexes
Build predictable PostgreSQL upserts by aligning conflict targets with partial unique indexes, tenant invariants, soft deletion, update rules, and concurrency tests.
2026-09-18 · 8 min read
JWT NumericDate precision and time validation
Validate JWT exp, nbf, and iat claims consistently by defining seconds, fractional precision, boundary comparisons, clock sources, leeway, and cross-runtime tests.
2026-09-18 · 8 min read
HTTP Accept negotiation for predictable APIs
Design content negotiation with explicit representation capabilities, correct Accept matching, deterministic preferences, cache-safe Vary fields, and contract tests.
2026-09-19 · 8 min read
JWE compression profiles, limits, and security
Process compressed JWE tokens safely with protected zip policy, strict algorithms, authenticated decryption, decompression limits, side-channel review, and vectors.
2026-09-19 · 8 min read
PostgreSQL exclusion constraints for non-overlapping data
Design PostgreSQL exclusion constraints with precise operators, range boundaries, tenant scope, null policy, deferral, concurrency handling, and migrations.
2026-09-19 · 8 min read
URL userinfo, authority parsing, and safe host validation
Validate URL destinations safely by parsing userinfo and authority components, constraining schemes and ports, redacting credentials, and checking redirects.
2026-09-19 · 8 min read
HTTP 103 Early Hints for safe resource preloading
Deploy HTTP 103 Early Hints safely by separating interim responses, selecting useful preload links, preserving fetch compatibility, and measuring intermediaries.
2026-09-19 · 8 min read
HTTP Alt-Svc deployment, security, and fallback
Deploy HTTP alternative services safely with preserved origin identity, certificate validation, bounded persistence, observable routing, and reliable fallback.
2026-09-20 · 8 min read
PostgreSQL generated columns for derived data
Design PostgreSQL generated columns with valid expressions, predictable types and collations, explicit write behavior, useful indexes, and safe migrations.
2026-09-20 · 8 min read
HTTP priority signals and resource scheduling
Use HTTP priority signals responsibly by modeling urgency and incremental delivery, preserving intermediary behavior, avoiding contention, and measuring rendering.
2026-09-20 · 8 min read
JSON Schema array matching with contains
Model JSON array match counts with contains, minContains, and maxContains by declaring the dialect, separating length rules, and testing composition boundaries.
2026-09-20 · 8 min read
JWK thumbprints for stable public-key identity
Compute and use JWK thumbprints correctly with key-type member selection, canonical JSON, UTF-8 hashing, Base64url encoding, trust policy, and vectors.
2026-09-20 · 8 min read
HTTP trailers and streaming content integrity
Implement HTTP trailers and Content-Digest checks with correct framing, exact representation bytes, intermediary compatibility, algorithm policy, and fallbacks.
2026-09-21 · 8 min read
PostgreSQL deferrable constraints and transaction design
Use PostgreSQL deferrable constraints safely by choosing eligible rules, controlling check timing, handling commit failures, testing concurrency, and planning migrations.
2026-09-21 · 8 min read
JSON Schema property dependencies with dependent keywords
Model conditional object requirements with dependentRequired and dependentSchemas by pinning the dialect, defining trigger presence, composing rules, and testing boundaries.
2026-09-21 · 8 min read
JWK use and key operations policy
Build a consistent JWK operation policy across use, key_ops, alg, key type, trusted discovery, rotation, and library behavior without weakening token validation.
2026-09-21 · 8 min read
HTTP stale cache directives for resilient delivery
Use stale-while-revalidate and stale-if-error with explicit freshness windows, safe revalidation, layered cache policy, protected content rules, and outage tests.
2026-09-21 · 8 min read
JSON Schema dynamic references and extensible recursion
Use $dynamicRef and $dynamicAnchor reliably by defining extension points, tracing dynamic scope, identifying bundled resources, pinning dialects, and testing recursion.
2026-09-22 · 8 min read
PostgreSQL row-level security policy design
Design PostgreSQL row-level security with explicit roles, command policies, tenant context, USING and WITH CHECK rules, safe helper functions, pooling, and adversarial tests.
2026-09-22 · 8 min read
PostgreSQL NULLS NOT DISTINCT uniqueness
Model nullable unique keys with PostgreSQL NULLS NOT DISTINCT by defining null identity, choosing constraints or indexes, cleaning collisions, handling concurrency, and testing ORMs.
2026-09-22 · 8 min read
OAuth pushed authorization requests in production
Deploy OAuth PAR safely with trusted metadata, protected back-channel submission, client authentication, exact request_uri handling, PKCE correlation, expiry, and operational tests.
2026-09-22 · 8 min read
HTTP message signatures and canonical components
Implement HTTP message signatures by selecting covered components, deriving canonical values, serializing Signature-Input correctly, enforcing key policy, and testing intermediaries.
2026-09-22 · 8 min read
JSON Schema encoded content and media validation
Design JSON Schema content handling by defining vocabulary behavior, decoding limits, media policy, decoded schemas, application checks, and portable tests.
2026-09-23 · 8 min read
PostgreSQL NOT VALID constraints for safer migrations
Roll out PostgreSQL constraints with NOT VALID by separating enforcement and scans, repairing old rows, controlling locks, and coordinating application deploys.
2026-09-23 · 8 min read
OAuth JARM validation and response processing
Validate OAuth JARM responses with trusted metadata, algorithm policy, decryption, claim and state checks, response modes, and replay-safe code exchange.
2026-09-23 · 8 min read
HTTP Prefer and Preference-Applied API design
Design HTTP preference handling with explicit support, tolerant fallbacks, return modes, bounded async work, cache rules, idempotency, and robust tests.
2026-09-23 · 8 min read
OpenAPI callbacks and runtime expressions
Specify OpenAPI callbacks with runtime expressions, safe URL handling, outbound controls, authentication, idempotent retries, generated clients, and tests.
2026-09-23 · 8 min read
JSON Schema vocabularies and dialect support
Design JSON Schema validation by pinning dialects, declaring required vocabularies, testing keyword support, controlling references, and planning upgrades.
2026-09-24 · 8 min read
PostgreSQL transition tables in statement triggers
Build PostgreSQL statement triggers with transition tables by defining row-set semantics, processing, recursion controls, security, performance, and tests.
2026-09-24 · 8 min read
OAuth resource indicators and audience-restricted tokens
Use OAuth resource indicators to request audience-restricted access tokens with clear URI policy, scope mapping, cache isolation, API validation, and tests.
2026-09-24 · 8 min read
HTTP 421 and connection coalescing
Handle HTTP 421 responses by aligning origin authority, TLS identity, connection coalescing, proxy routing, retry safety, observability, and regression tests.
2026-09-24 · 8 min read
OpenAPI links and runtime expressions
Design OpenAPI links with runtime expressions, stable operation targets, parameter serialization, authorization boundaries, tooling checks, and fixtures.
2026-09-24 · 8 min read
JSON Schema format vocabularies and assertion policy
Design portable JSON Schema format validation by choosing dialect semantics, assertion policy, checker support, application constraints, and conformance tests.
2026-09-25 · 8 min read
PostgreSQL COPY FREEZE for controlled bulk loads
Plan PostgreSQL COPY FREEZE workflows with eligibility checks, MVCC visibility controls, table preparation, performance measurement, rollback, and restore tests.
2026-09-25 · 8 min read
OAuth authorization response issuer validation
Implement OAuth authorization response issuer validation with transaction binding, discovery policy, mix-up defenses, error handling, migration, and tests.
2026-09-25 · 8 min read
HTTP Content-Location representation design
Use HTTP Content-Location correctly by modeling representation identifiers, relative URI resolution, selected variants, write responses, cache rules, and tests.
2026-09-25 · 8 min read
OpenAPI parameter content and structured values
Design OpenAPI parameters with content by choosing schema alternatives, one media type, exact wire encoding, tool support, validation boundaries, and fixtures.
2026-09-25 · 8 min read
JSON Schema conditional validation with if, then, and else
Design maintainable JSON Schema conditionals by defining presence rules, decision tables, branch composition, annotation behavior, and portable tests.
2026-09-26 · 8 min read
PostgreSQL MERGE concurrency and data integrity
Design PostgreSQL MERGE workflows with deterministic sources, ordered actions, concurrency controls, trigger awareness, retry policy, observability, and tests.
2026-09-26 · 8 min read
OAuth device authorization grant polling and UX
Implement OAuth device authorization with trusted verification UX, protocol-aware polling, code protection, cancellation, token handling, observability, and tests.
2026-09-26 · 8 min read
HTTP 207 Multi-Status and partial-result handling
Handle HTTP 207 Multi-Status responses by parsing WebDAV XML, mapping resource and property outcomes, defining retries, preserving identity, and testing clients.
2026-09-26 · 8 min read
OpenAPI 3.1 webhooks as reliable event contracts
Design OpenAPI 3.1 webhook contracts with stable events, precise requests, signatures, destination controls, retries, versioning, tooling checks, and fixtures.
2026-09-26 · 8 min read
JSON Schema dynamic property names and pattern rules
Design JSON Schema dictionaries with propertyNames, patternProperties, anchored expressions, compatible overlaps, explicit extra values, and portable tests.
2026-09-27 · 8 min read
PostgreSQL LISTEN and NOTIFY reliability
Use PostgreSQL LISTEN and NOTIFY with committed subscriptions, dedicated pooled sessions, small signals, durable state, reconnect recovery, and load tests.
2026-09-27 · 8 min read
OAuth Rich Authorization Requests in production
Implement OAuth Rich Authorization Requests with registered types, exact JSON, PAR or request objects, consent, grant binding, API enforcement, and tests.
2026-09-27 · 8 min read
HTTP 202 Accepted asynchronous workflow design
Design HTTP 202 workflows with atomic job creation, idempotent submission, authorized status resources, bounded polling, cancellation, results, and cleanup.
2026-09-27 · 8 min read
OpenAPI security requirement composition
Model OpenAPI authentication with AND and OR semantics, operation overrides, optional access, exact scheme names, OAuth scopes, runtime checks, and tests.
2026-09-27 · 8 min read
JSON Schema unevaluatedItems and array composition
Design composable JSON Schema arrays with prefixItems, items, contains, successful evaluation annotations, explicit closure, pinned dialects, and portable tests.
2026-09-28 · 8 min read
PostgreSQL logical replication slot reliability
Operate PostgreSQL logical replication slots with clear ownership, WAL budgets, durable checkpoints, schema-change policy, failover planning, recovery, and tests.
2026-09-28 · 8 min read
OAuth mTLS and certificate-bound access tokens
Implement OAuth mutual TLS with trusted endpoint metadata, client authentication, certificate-bound tokens, secure proxy identity, rotation, API validation, and tests.
2026-09-28 · 8 min read
HTTP conditional writes and 412 responses
Prevent lost updates with strong ETags, If-Match, atomic precondition evaluation, representation-aware validators, explicit conflict UX, proxy controls, and tests.
2026-09-28 · 8 min read
OpenAPI discriminator and polymorphic schemas
Design OpenAPI polymorphism with independently valid oneOf branches, required literal tags, explicit discriminator mappings, compatible evolution, tooling checks, and fixtures.
2026-09-28 · 8 min read
JSON Schema references and sibling keywords
Apply JSON Schema $ref across drafts, sibling keywords, bundlers, base URIs, cycles, and anchors so every validator executes the contract you published.
2026-09-29 · 8 min read
PostgreSQL search_path and object resolution
Lock PostgreSQL search_path for roles, functions, extensions, and migrations so every session resolves the intended tables, functions, and operators.
2026-09-29 · 8 min read
OAuth JWT bearer client assertions
Issue OAuth JWT bearer client assertions with pinned audiences, short lifetimes, unique identifiers, signing-key rotation, and token-endpoint checks that fail closed.
2026-09-29 · 8 min read
OpenAPI parameter serialization styles
Design OpenAPI path, query, header, and cookie parameters so style, explode, and encoding match what servers and generated clients put on the wire.
2026-09-29 · 8 min read
HTTP Idempotency-Key retries that stay safe
Design Idempotency-Key retries with scoped keys, request fingerprints, stored outcomes, and replay rules so a lost response cannot repeat the side effect.
2026-09-29 · 8 min read
JSON Schema uniqueItems and deep equality
Design JSON Schema array uniqueness with deep equality, stable object comparison, numeric normalization, explicit business keys, dialect pins, and tests.
2026-09-29 · 8 min read
PostgreSQL identity column ownership
Operate PostgreSQL identity columns with clear ownership, insert policy, restart procedure, privilege boundaries, import recovery, and failover tests.
2026-09-29 · 8 min read
Quartz and Unix cron compatibility
Schedule jobs safely across Quartz and Unix cron by pinning field counts, weekday numbers, time zones, special characters, and next-run preview tests.
2026-09-29 · 8 min read
Resumable Server-Sent Events design
Design resumable Server-Sent Events with durable event IDs, Last-Event-ID replay, bounded retention, proxy streaming, and duplicate-safe client handling.
2026-09-29 · 8 min read
MATLAB and JSON array orientation
Exchange MATLAB arrays as JSON by fixing vector orientation, nested rows, empty shapes, NaN handling, precision limits, and a payload review checklist.
2026-09-29 · 8 min read
OpenAPI nullability across 3.0 and 3.1
Design OpenAPI nullability that stays valid across 3.0 nullable, 3.1 type unions, generators, and runtime validators without merging omission and null.
2026-09-30 · 8 min read
PostgreSQL citext for case-insensitive identity
Choose PostgreSQL citext or a lower() unique index with extension ownership, locale limits, operator matches, ORM mappings, and migration tests before release.
2026-09-30 · 8 min read
Translate cron schedules into systemd OnCalendar
Translate five-field cron into systemd OnCalendar with weekday names, AND semantics, time zones, persistence, accuracy, and a preview of the next runs.
2026-09-30 · 8 min read
Operate OAuth token introspection safely
Run OAuth token introspection with caller authentication, active responses, audience checks, caches, revocation, and diagnostics that never store the token.
2026-09-30 · 8 min read
Keep YAML dates as strings across loaders
Keep YAML calendar values as strings by pinning the schema, quoting dates, controlling time zones, and testing the JSON each loader emits before deploy.
2026-09-30 · 7 min read
Choose PostgreSQL statement, lock, and idle timeouts
Set PostgreSQL statement, lock, and idle-in-transaction timeouts by what each one cancels, which session stores it, and how a connection pooler resets it.
2026-10-01 · 8 min read
Handle OAuth step-up authentication challenges
Handle OAuth step-up when a token's acr or auth_time is too weak, and use the 401 challenge to request a fresh authentication instead of a blind retry.
2026-10-01 · 7 min read
Build correct URLs from OpenAPI server variables
Build OpenAPI server URLs from variables, defaults, and enums, then resolve relative servers and path joins before a generated client calls the wrong host.
2026-10-01 · 7 min read
Validate JWT crit header extensions
Accept or reject JWT crit extensions deliberately using protected-header rules, unknown names, and the 401 that is not a bad signature or expired exp.
2026-10-01 · 8 min read
Trust the HTTP Forwarded header at the edge
Trust the HTTP Forwarded header only after the edge proxy replaces it, and keep X-Forwarded-For on that same documented path through every trusted proxy hop.
2026-10-01 · 7 min read
Choose UUID v7 when time order matters
Use UUID version 7 when insertion order should follow creation time, and keep version 4 when the identifier must not reveal when it was minted.
2026-10-14 · 8 min read
Encapsulate CSS with @scope
Limit CSS with @scope, a lower boundary, and proximity, then confirm the winning declaration in computed styles instead of trusting source order alone.
2026-10-14 · 8 min read
Use partitioned cookies for embedded sites
Set Partitioned cookies for cross-site embeds, key them to the top-level site, and test that a second embedder does not receive the first embedder's cookie.
2026-10-14 · 7 min read
Expand cron nicknames before you trust them
Expand crontab nicknames such as @daily and @hourly into five fields, then preview those fields in the daemon's timezone before you depend on them.
2026-10-14 · 7 min read
Calculate WCAG contrast from painted colors
Compute WCAG contrast from composited sRGB colors, compare the 4.5:1 and 3:1 thresholds, and recheck edges when tools use different linearization cutoffs.
2026-10-14 · 8 min read
Mix CSS colors in a named interpolation space
Mix CSS colors in a named color space, normalize percentages that do not sum to 100, and choose a hue path so the midpoint is the color you meant to ship.
2026-10-15 · 8 min read
Use PostgreSQL AT TIME ZONE in one direction
Apply PostgreSQL AT TIME ZONE once. A plain timestamp becomes an instant, and timestamptz becomes a wall clock in the zone you named, not another instant.
2026-10-15 · 8 min read
Read the time prefix on a ULID
Decode a ULID time prefix from Crockford base32, compare monotonic and random generators, and sort canonical uppercase text instead of mixed-case copies.
2026-10-15 · 8 min read
Check a subresource integrity attribute
Check subresource integrity by using the strongest hash in the attribute, comparing it with the fetched bytes, and setting crossorigin for other origins.
2026-10-15 · 8 min read
Separate a cron schedule zone from the job TZ
Set the cron schedule zone with the variable your daemon actually reads, and keep the job TZ environment from being mistaken for the clock that fires the job.
2026-10-15 · 8 min read
Use CSS light-dark() with a real color scheme
Resolve CSS light-dark() from the used color-scheme, inherit that property from a real ancestor, and check the painted hex before you trust the source.
2026-10-16 · 8 min read
Bucket timestamps with PostgreSQL date_bin
Align PostgreSQL date_bin to an origin you choose, treat the stride as fixed microseconds, and use date_trunc when the contract is a calendar boundary instead.
2026-10-16 · 8 min read
Read a snowflake id without losing the sequence
Decode a 64-bit snowflake by naming its epoch and field widths, shift off the low 22 bits for the clock, and keep the decimal id as a string in JSON.
2026-10-16 · 8 min read
Scan text with a sticky JavaScript regex
Use the JavaScript y flag when the next match must start at lastIndex, and keep g without y when the search is allowed to skip ahead to a later hit.
2026-10-16 · 7 min read
Choose now(), statement time, or the wall clock
Pick PostgreSQL now(), statement_timestamp(), or clock_timestamp() on purpose so a transaction, a statement, and the wall clock stop sharing one frozen instant.
2026-10-16 · 8 min read
Label binary and decimal byte sizes on purpose
Keep a raw byte count, then label it with SI prefixes or IEC prefixes so a binary converter and a decimal bill stop describing one size with two words.
2026-10-17 · 8 min read
Choose svh, lvh, or dvh for mobile page height
Size mobile layouts with the small, large, or dynamic viewport, then check the computed pixel height with the browser chrome and the keyboard in both states.
2026-10-17 · 8 min read
Use overflow clip when sticky must see past a card
Clip a card without creating a scrollport, and read the computed overflow axes so a sticky header still sticks to the page that actually scrolls.
2026-10-17 · 8 min read
Add PostgreSQL months without a silent day clamp
Add a month interval in one step, keep days separate, and avoid justify_days when the calendar day has to survive February.
2026-10-17 · 8 min read
Use the JavaScript regex v flag as a set operator
Write Unicode set difference and intersection with the v flag, escape literal syntax characters, and keep the u flag for patterns that must not use set operators.
2026-10-17 · 8 min read
Split identifiers before you change their case
Convert camel case, snake case, and kebab case with the splitter each output actually uses, and keep acronyms and separators intact before you rename a field.
2026-10-18 · 8 min read
Encode one URL component, not the whole URL
Use encodeURIComponent on a single URL piece, keep reserved punctuation outside it, and treat a malformed percent escape as a broken input.
2026-10-18 · 8 min read
Turn JSON objects into MATLAB struct assignments
Generate MATLAB struct lines from one JSON object, including dynamic field names, row vectors, and the errors for nested objects and mixed arrays.
2026-10-18 · 8 min read
Convert decimal integers before you trust hex output
Feed the number-bases tool plain decimal digits, stop before a fraction or a 0x prefix, and stay inside the integers JavaScript can store exactly.
2026-10-18 · 8 min read
Read named captures beside the numbered group list
Match with named groups, keep the pattern global for the tester, and record each name beside the numbered slot the panel actually prints.
2026-10-18 · 8 min read
Format JSON without mistaking a rewrite for an edit
Pretty-print and minify JSON with the parser's stored values, including negative zero, exponents, duplicate keys, escaped slashes, and the trailing newline.
2026-10-19 · 8 min read
Beautify CSS only when every semicolon is a declaration
Run the CSS beautifier on plain declarations, and keep comments, content strings, and data URIs out of a transform that splits on every semicolon.
2026-10-19 · 8 min read
Generate a password from the alphabet you actually enabled
Build a local password from the checked classes, read the 4 to 128 clamp, and account for modulo bias before you call the draw a policy match.
2026-10-19 · 8 min read
Convert PEM line breaks without losing the block you meant
Escape and restore PEM line breaks, then diff blank lines, indentation, quotes, and doubled backslash sequences before the value goes into an env file.
2026-10-19 · 8 min read
Parse a Unix seconds field without inventing 1970
Read the timestamp tool's Unix box as seconds, treat an empty box as the epoch, floor ISO milliseconds, and write a zone on every local date-time.
2026-10-19 · 8 min read
Format SQL without mistaking a space for a rewrite
Format SQL in the default dialect and read the spacing: keyword case is preserved, unknown functions gain a space, and dollar-quoted strings are rejected.
2026-10-20 · 8 min read
Parse MATLAB matrix literals without losing a row
Convert JSON and MATLAB matrix literals by checking row shape, rectangular gaps, Number() prefixes, and the silent empty matrix returned for a non-array.
2026-10-20 · 8 min read
Generate a UUID batch from a count that is a number
Generate local version 4 UUID batches from the count field: blank values clamp to one id, decimals truncate, and a non-numeric count prints an empty list.
2026-10-20 · 7 min read
Read a text diff without counting the pilcrows
Read a browser text diff by separating the edit from the display: newlines become pilcrows, HTML is escaped, and semantic cleanup can widen a small change.
2026-10-20 · 8 min read
Assemble a Portainer env block from the first value
Assemble a Portainer env block from KEY=value lines and check duplicates, quotes, export prefixes, placeholders, and which Compose names the scan sees.
2026-10-20 · 8 min read
Convert YAML scalars without a surprise null
Convert YAML to JSON without mistaking null: non-finite scalars collapse, merge keys stay literal, and JSON-to-YAML quotes strings that would change type.
2026-10-21 · 8 min read
Sign a test JWT with the algorithm button
Build a local test JWT and read the header that was signed: the algorithm button wins, both sides must be objects, and extra token segments are ignored.
2026-10-21 · 8 min read
Decode standard Base64 without a URL alphabet
Decode standard Base64 without assuming URL safety: padding can be omitted, whitespace is skipped, and bytes that are not valid UTF-8 are replaced in output.
2026-10-21 · 7 min read
Preview cron as five UTC instants
Read five cron previews as UTC instants: six fields begin with seconds, day-of-month and weekday combine with OR, and schedule nicknames are case-sensitive.
2026-10-21 · 8 min read
Fit a QR payload at error correction M
Fit a payload into a QR symbol at error correction M: the encoder picks a mode, spaces count, and version 40 is the last size this generator will draw.
2026-10-21 · 7 min read
Read Markdown breaks and the source counters
Read a Markdown preview when single newlines become br tags, count words with the markers included, and tell a blank preview from a file that still has lines.
2026-10-22 · 8 min read
Export a Markdown PDF under the first h1
Name a Markdown PDF from the first level-one heading, see which characters survive the file name, and know which HTML the sanitizer removes before export.
2026-10-22 · 8 min read
Encode HTML entities with one textarea pass
Encode and decode HTML entities with the textarea the page uses: quotes stay literal, one pass is not two, and a tag in the decode box is not an element.
2026-10-22 · 8 min read
Pretty-print XML without a second indent
Pretty-print XML with this formatter's indent rules: short tag names do not indent, minify does not strip text, and parser errors are copied as written.
2026-10-22 · 8 min read
Hash the bytes in the box, newline included
Compare SHA-256 and SHA-512 hex of the exact UTF-8 you pasted, including a trailing newline, and keep a blank box separate from the empty-string digest.
2026-10-22 · 7 min read