Compute a 32-character MD5 checksum of text or a file in this tab. Web Crypto omits MD5, so this page uses js-md5 locally. MD5 has been collision-broken since 2004: use it to match legacy checksums, never for signatures or passwords. A mismatch is usually a trailing newline or the wrong algorithm. Nothing is uploaded.
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MD5 produces a fixed 128-bit digest, 16 bytes, 32 hex characters. Web Crypto deliberately omits it (the API ships only algorithms considered secure), so this page uses the js-md5 library, still entirely in your browser. MD5 has been broken for collision resistance since 2004: use it to match legacy checksums, never for security.
The break is not theoretical: crafting two different inputs with the same MD5 digest takes under a second on ordinary hardware, and chosen-prefix collisions (two meaningful colliding documents) are within hobbyist budgets. What still holds is second-preimage resistance: nobody can produce a file matching your existing file's MD5, which is exactly why MD5 remains serviceable for detecting accidental corruption and nothing more. The empty string's digest, d41d8cd9…ecf8427e, is worth recognizing in logs: it means something hashed nothing.
If an MD5 does not match the published value, check the byte-level suspects first (trailing newline, CRLF, BOM), and count characters: a 40-hex value against your 32-hex output means the source published SHA-1, not MD5. If you are choosing an algorithm rather than matching one, stop here and use SHA-256, same tool, the row directly below MD5.
Only where a legacy system demands MD5: old checksum files, an ETag scheme you cannot change, cache keys in an existing format.
This page is a focused view of theHash Generator: SHA-256, SHA-512, SHA-1, MD5, which has the full set of options.
For non-adversarial jobs, yes, detecting accidental corruption or keying a cache is fine. It is unsafe wherever an attacker benefits from crafting two inputs with the same hash: signatures, certificates, password storage.
The Web Crypto API only ships algorithms considered secure; MD5 and SHA-1 checksum use cases are left to libraries. That is why this page uses js-md5 while SHA-256 uses crypto.subtle.
Not by reversing it, but common short inputs are trivially found in precomputed lookup tables, another reason never to “hash” secrets with bare MD5.