UUID Generator
Generate random UUID v4 (GUID) identifiers — one or hundreds at a time.
Uses the Web Crypto API on your device. Nothing is generated on a server or sent anywhere.
About this tool
This free tool generates version 4 UUIDs (Universally Unique Identifiers, also called
GUIDs). A UUID v4 is a 128-bit identifier formatted as
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where 122 of the bits are random.
They are used as database keys, API request IDs, file names and session tokens.
Generation uses your browser's built-in crypto.getRandomValues() — a
cryptographically secure random source — so the UUIDs are suitable for anything from
test fixtures to production primary keys. Your device never contacts a server during
generation, so the values cannot leak.
Need hashes instead of unique IDs? Try the Hash Generator, or format API payloads with the JSON Formatter.
Frequently asked questions
Are these UUIDs really unique?
Version 4 UUIDs contain 122 random bits. The probability of a collision among trillions of generated UUIDs is astronomically small — small enough that v4 uniqueness is treated as guaranteed in practice. Randomness comes from your browser's cryptographic random number generator.
Can someone guess a UUID I generated?
Practically no. With 122 random bits, brute-forcing a specific v4 UUID is infeasible. Still, UUIDs are identifiers, not secrets — do not use them as authentication tokens or passwords.
What is the difference between v4 and other versions?
v1 uses timestamps and MAC addresses (leaks information), v3/v5 derive from a name via hashing (deterministic), and v7 encodes a timestamp (sortable). v4 is fully random and the right default unless you need a specific property of another version.
Is there a limit on how many I can generate?
No. Generation runs locally in your browser with no server involved — generate as many as you need, in bulk if required.