MD5 vs bcrypt — Which Should You Use?
MD5 and bcrypt both produce a string from your input, but they solve opposite problems. MD5 is a fast, deterministic checksum: the same input always yields the same 32-char digest, which is perfect for legacy deduplication and terrible for passwords. bcrypt is a slow, salted password hash: every call yields a different 60-char hash thanks to a random salt and tunable cost. Fast integrity work wants MD5 or SHA-256; anything that must resist offline guessing wants bcrypt. Both tools run 100% in your browser.
Use MD5 when
- You must match an existing legacy checksum, dedup column, or non-security fingerprint that hard-codes MD5.
- The hash is not protecting a secret. A collision would be harmless noise, not a forgery.
- Every caller must produce the same digest for the same bytes, deterministically.
- You are verifying past data, not designing a new integrity system.
Use bcrypt when
- You are storing passwords or secrets that must survive offline brute-force after a leak.
- You need per-record random salts so identical passwords never look alike in the database.
- You want a tunable cost factor to keep pace as hardware gets faster, unlike a fixed fast hash.
- You need an adaptive hash you can verify by re-hashing, not by string comparison of digests.
Side by side
| MD5 Hash Generator | bcrypt Password Hasher | |
|---|---|---|
| Purpose | Fast legacy checksum | Slow password hash |
| Salt | None, deterministic | Random per hash, embedded in output |
| Same input twice | Identical 32-char digest | Different 60-char hash each time |
| Output | 32 hex chars | 60 chars ($2b$10$...) |
| Speed | Fast by design | Deliberately slow (2^cost rounds) |
| Collision resistance | Broken | Not applicable, brute force is the threat |
| Best for | Legacy fingerprints | Passwords and secrets |
| Where it runs | Browser, no upload | Browser, no upload |
Putting a fast hash on passwords lets attackers test billions of guesses per second per GPU. bcrypt's cost and per-hash salt make each guess expensive. Neither tool uploads your input; both run entirely in the browser.
If an attacker guessing the input could matter, MD5 is the wrong tool. Use bcrypt for any secret that must survive a leak, and reserve MD5 for legacy reads where a collision would not help an attacker. Fast hashes are for fingerprints, slow hashes are for credentials.