2026-10-22 · 5 min read · Rahul Chitturi
- hash
- checksum
- debugging
The hash page digests the box as UTF-8 and prints lowercase hex. SHA-256 and SHA-512 are the only choices. There is no trim, no newline stripping, and no base64 form. An empty box is special: the page clears the digest and does not hash the empty string.
The note under the box says hashes are not password storage. The same rule is why two pastes of the same word can disagree. The bytes differed.
Separate a blank box from an empty digest
A box with no characters shows no hex. The SHA-256 digest of the empty string is e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855, and this page will not print it. A box that contains a space is not blank. Its SHA-256 is 36a9e7f1c95b82ffb99743e0c5c4ce95d83c9a430aac59f84ef3cbfab6145068. The character 0 is also hashed. Its SHA-256 is 5feceb66ffc86f38d952786c6d696c79c2dbc239dd4e91b46729d73a27fb57e9.
flashman is 9c35b425f251667dba79f189e990538644b9132e6da3d003979391e3c0f64c7e in SHA-256. The SHA-512 hex of the same eight letters is 128 characters and starts d1557ffb04b50111. Switching the button hashes the same box again. It does not encode the other digest.
- Clear the box to see no digest.
- Do not compare that blank with the empty-string hash.
- Count spaces before the first character.
- Read SHA-512 as 128 hex characters.
Hash the newline the editor added
flashman followed by LF is 0fb270e290b457dfe7a7df2a65c073ccf848d44a6a0bc2abb896b99048493848. The same letters followed by CRLF are 05fc1b0a4ef6f462b099c5d21242ed9a0194da3510650842903f1899eee9d9f4. A leading space changes the digest again, to 0d1455aa8c0bc8f69354cc652307d35c2aa0bac90e895c2b7fdb7a3a3c974ead. The page does not show the length of the input.
é is the two UTF-8 bytes C3 A9, and its SHA-256 is 4a99557e4033c3539de2eb65472017cad5f9557f7a0625a09f1c3f6e2ba69c4c. 🙂 is the four-byte sequence F0 9F 99 82, and its SHA-256 is d06f1525f791397809f9bc98682b5c13318eca4c3123433467fd4dffda44fd14. A hash of those characters is not a hash of their HTML entities.
Compare hex of the same bytes
Copy the digest only after the box matches the file, including the final newline. Diff will show a newline the eye skips. The Base64 page is a different encoding of text, and a digest of the Base64 string is not a digest of the decoded text.
Use the hash tool for SHA-256 or SHA-512 hex, diff to find the extra byte, and the Base64 tool when the other system sent the text in another alphabet. Quote the algorithm and whether the last byte was a newline. The page will not turn the hex into a Subresource Integrity token.