MD5 Hash Generator

Type anything and all four forms of the hash appear at once: 32 or 16 characters, upper or lower case. They are the same hash; the 16-character one is just the middle slice of the 32-character version, a habit from old systems that some integrations still expect.

MD5 turns any input into a fixed 128-bit fingerprint. Same text in, same hash out, every time. Change one letter and the whole hash changes.

Still reasonable uses

• Checking a downloaded file against a published checksum
• Cache keys and deduplication, where nobody is attacking you
• Integrations that simply require it

Uses to avoid

Passwords. MD5 is fast by design, and fast is exactly wrong for password hashing. GPU rigs test billions of candidates per second; the plaintext passwords in every leaked database you have read about were recovered that way. Use bcrypt or argon2 on the backend.

Signatures and tamper-proofing are out too. Collisions have been manufactured since 2004, which retired MD5 as a security function a long time ago.

About Chinese text

The hash runs over UTF-8 bytes, which is what Linux md5sum does, so results line up. But if one side encodes the same text in GBK, the hashes differ while the text looks identical. When a hash "doesn't match" for no visible reason, check the encoding first, then trailing whitespace, then whether the other system salts it.