UUID & Hash Generator
Generate random UUID v4 values, or hash any text with SHA-1/256/384/512, using your browser's built-in Web Crypto API. No library, no network call.
UUID v4
Hash generator
Batch mode
Generate multiple UUIDs
Hash multiple lines
A note on MD5
This tool deliberately does not offer MD5 or SHA-1 for anything security-sensitive — both are broken for collision resistance. SHA-1 is included here only because some legacy systems still expect it for non-security checksums. For anything protecting real data, use SHA-256 or better.
FAQ
Could two generated UUIDs ever collide?
A UUID v4 has 122 random bits (the other 6 are fixed to mark the version and variant). To have a 50% chance of any collision, you'd need to generate roughly 2.7 quintillion of them — in practice, treat a v4 UUID as unique.
Why only v4? What about v1 or v7?
This tool generates v4 (fully random) specifically. v1 embeds a timestamp and MAC address; v7 (newer, RFC 9562) embeds a timestamp for sortable, index-friendly IDs. If you need time-ordered IDs for a database primary key, v7 is usually the better choice — v4 is the right default when you just need a unique, unguessable identifier.
Can I use SHA-256 to hash passwords?
Not safely on its own. SHA-256 is fast by design, which is exactly wrong for password storage — it makes brute-forcing leaked hashes cheap. Use a purpose-built password hash (bcrypt, scrypt, or Argon2) with a per-user salt instead; the general-purpose hashes here are for integrity checks (verifying a file or payload wasn't altered), not credential storage.
Can a hash be reversed back to the original text?
No — a cryptographic hash is one-way by design. The same input always produces the same output, which makes hashes useful for comparison and integrity checks, but there's no operation that recovers the input from the digest alone.