Hash Generator: MD5, SHA-1, SHA-256 and What They're Used For
A cryptographic hash takes any input and produces a fixed-length 'fingerprint' that uniquely (with overwhelming probability) identifies it. Hashes are used for file integrity, password storage, digital signatures, and version IDs.
A good hash function has three properties: deterministic (same input always produces same output), unique (different inputs almost always produce different outputs), and one-way (you can't derive the input from the hash). The hashes most people encounter are MD5 (legacy, broken), SHA-1 (broken in some uses), and SHA-256 (modern standard).
Common hash algorithms
| Algorithm | Output length | Status |
|---|---|---|
| MD5 | 128 bits / 32 hex chars | Cryptographically broken — only use for non-security purposes (file integrity) |
| SHA-1 | 160 bits / 40 hex chars | Cryptographically broken for collision resistance — phasing out |
| SHA-256 | 256 bits / 64 hex chars | Current standard |
| SHA-512 | 512 bits / 128 hex chars | Same family, larger output |
| BLAKE3 | 256 bits or arbitrary | Modern, very fast — gaining adoption |
Extended FAQ
Can a hash be reversed?
Not directly. For short or common inputs (passwords like '123456'), attackers use precomputed tables (rainbow tables). That's why password storage uses 'salted' hashes with bcrypt/scrypt/Argon2 — making each hash effectively unique.
Are my pasted strings stored?
No — runs entirely in your browser.