About MD5Calc
What this is
Hash tools that run in your browser. Nothing you type or select is uploaded.
| Tool | Does |
|---|---|
| Hash calculator (home page) | MD5, SHA-1, SHA-256 and SHA-512 of text, hashed as UTF-8. |
| HMAC calculator | HMAC under all four algorithms, text or hex key. Matches OpenSSL and Node. |
| File hash | The four digests of a file you choose, up to 256 MB, with a field to paste the published checksum. |
| Hash comparison | Compares two digests ignoring case, spaces, colons and an algorithm prefix; names the algorithm from the length. |
How it computes them
MD5 is a pure-JavaScript implementation and works anywhere. SHA-1, SHA-256 and SHA-512 use crypto.subtle, which browsers only provide on https:// and localhost; on plain HTTP the home page shows MD5 and says the others need https. HMAC is built from these digests by the RFC 2104 construction and is checked in this repository's tests against Node's crypto.createHmac, including keys longer than the block size.
What a hash proves
A matching digest shows two byte sequences are identical (for SHA-256 and SHA-512, to cryptographic confidence). It does not show the publisher is who you think: a checksum served from the same page as the download protects against corruption, not against someone who replaced both. MD5 and SHA-1 do not protect against an adversary at all.