UUID & Hash Generator

A UUID (universally unique identifier) is a 128-bit value used to identify something — a database row, a session, a request — without a central authority handing out IDs. Version 4 is generated from random bits, which is what almost every application actually wants. Other versions exist (v1 encodes a timestamp and MAC address, v5 derives an ID deterministically from a namespace and name) but this tool only generates v4, since it covers the overwhelming majority of use cases without the tradeoffs those versions carry.

A hash is a fixed-length fingerprint of some input — the same input always produces the same hash, and changing even one byte changes the hash completely. Common uses: verifying a downloaded file matches a published checksum, deduplicating content, or generating a stable lookup key from arbitrary text.

No — do not use MD5 or SHA-1 for passwords or anything security-sensitive. Both are cryptographically broken; MD5 in particular has practical collision attacks. This tool includes them only for legacy compatibility and non-security checksums (matching an old git blob hash, for example). SHA-256 and SHA-512 are the right choice for anything where security matters, and even those are the wrong tool for password storage specifically — passwords need a slow, salted algorithm designed for that purpose (bcrypt, scrypt, Argon2), not a general-purpose hash.

No. UUIDs are generated with crypto.randomUUID() and hashes are computed with the Web Crypto API (or a local MD5 implementation, since Web Crypto does not support MD5) — entirely client-side. Files are read and hashed in memory; nothing is uploaded anywhere.