Hash Generator

Where each digest comes from

The SHA family is computed by your browser's own Web Crypto implementation, which is typically native code and is the same implementation everything else in your browser uses, so a mismatch is impossible by construction. MD5 and CRC32 are computed here in JavaScript, because neither is in the Web Crypto specification - MD5 was excluded deliberately, since the working group did not want a broken hash to be a one-liner in every browser, and CRC32 is not a hash at all.

One consequence worth knowing: Web Crypto is only available in a secure context, so on a plain HTTP page the SHA algorithms genuinely cannot run. This tool says so explicitly rather than producing nothing, because an empty result looks like a problem with your input.

MD5 and SHA-1 are here, and they are labelled

Both are broken against an adversary. MD5 collisions can be produced in seconds, and SHA-1's first practical collision was demonstrated in 2017. Neither proves that a file came from where it claims to.

They are still computed here because they are still genuinely needed: MD5 is the ETag and Content-MD5 of a decade of APIs and the published checksum of thousands of artefacts, and SHA-1 is what git uses for object ids. Withholding them would push you to a tool that says nothing at all about their weakness, which is worse. So they compute, with the caveat next to the value.

• SHA-1, SHA-256, SHA-384, SHA-512 via Web Crypto
• MD5 to RFC 1321, verified against the specification's own test vectors
• CRC32 with the IEEE polynomial that ZIP, PNG and gzip use
• Hex and Base64 output - the latter is what Content-MD5 and Subresource Integrity carry

No hash here belongs near a password

This is the single most consequential misuse of the thing this page computes, so it is worth being blunt: SHA-512 is not a safe password hash, and neither is SHA-256 with a salt. Speed is the entire purpose of a general-purpose hash and the entire problem for a password, because it is exactly what makes brute-forcing cheap - a commodity GPU tries billions of SHA-256 guesses per second. Passwords need bcrypt, scrypt or Argon2, which are deliberately slow and deliberately memory-hard.

What it will not do

It hashes text, not files. A file hash is a genuinely useful thing to want, and it is also a one-line shell command - shasum -a 256 yourfile - that does not require trusting a web page with the file.

It also will not reverse a hash. Nothing can: a hash is one-way by design, and the services that claim otherwise are looking your value up in a table of precomputed common inputs, which works only for short or unsalted ones. And it does not compute HMACs, which need a key and are a different operation.