2026-09-12 · 6 min read · Rahul Chitturi
- http
- redirects
- api-debugging
A POST can reach an endpoint as GET after a redirect, or it can repeat its body against a second host when the caller expected a safe navigation. The outcome depends on the redirect status, client implementation, original method, and redirect policy.
Browsers, command-line clients, SDKs, and proxies do not always expose the same defaults. Inspect the complete chain before changing the API handler that receives the final request.
Record every redirect hop
Capture the original method and URL, each status and Location value, the method selected for the next hop, whether a body was sent, and the final response. Redact authorization, cookies, and private payloads.
- Test 301 and 302 behavior with the actual client.
- Expect 303 to select GET or HEAD for the follow-up.
- Use 307 or 308 only when method and content replay are intended.
- Resolve relative Location values against the current URL.
Choose redirect semantics deliberately
Avoid redirects for machine API writes when the client can call the canonical endpoint directly. If migration requires one, select a status that matches the required method behavior and confirm that replaying the request body is safe.
Do not forward credentials automatically across an origin change. Reapply authentication only under an explicit trusted policy, and make state-changing operations idempotent where transport retries or preserved-method redirects can duplicate them.
Reproduce with safe Flashman fixtures
Use the URL tool to inspect each Location, JSON formatter for a synthetic request body, diff for hop-by-hop metadata, and timestamp converter for sanitized traces. Browser formatting tools do not emulate every redirect client.
Test all five redirect statuses, POST and PUT, relative and absolute targets, query strings, origin changes, HTTPS upgrades, loops, cached permanent redirects, non-rewindable streams, retries, and each production SDK.