UUID Generator
Generate cryptographically random UUID v4 values instantly. Bulk mode up to 100 UUIDs at once. Uses the browser's built-in Web Crypto API.
Runs entirely in your browser — nothing is sent to any serverGenerated UUIDs will appear here.
About UUID v4
What is a UUID v4?
UUID stands for Universally Unique Identifier. A version 4 UUID is a 128-bit value formatted as 32 hexadecimal characters in the pattern xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The "4" in position 13 identifies it as version 4. All other digits are random.
Cryptographic randomness
This tool uses crypto.randomUUID(), part of the Web Crypto API built into every modern browser. It pulls entropy from your operating system's CSPRNG (cryptographically secure pseudorandom number generator), the same source used for TLS key generation.
When to use UUIDs
UUIDs work best as primary keys in distributed databases where multiple nodes must generate IDs without coordinating with a central authority. They're also common for session tokens, file upload identifiers, and anywhere a unique string is needed without a predictable sequence.
Collision probability
UUID v4 has 122 bits of randomness. The probability of generating two identical UUIDs across 1 billion UUIDs per second for the next 100 years is astronomically small, roughly 50% after generating 2.71 quintillion values. For any practical application, collisions are not a concern.
How to use
- 1Set the quantity
Choose how many UUIDs you need — from 1 to 100 — using the number input.
- 2Click Generate
The tool generates cryptographically random UUID v4 values instantly using your browser's Web Crypto API.
- 3Copy your UUIDs
Copy a single UUID with its individual button, or copy all at once with "Copy all".
Frequently asked questions
What is a UUID?
UUID stands for Universally Unique Identifier. It is a 128-bit label formatted as 8-4-4-4-12 hexadecimal digits (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are used as unique IDs for database records, API resources, file uploads, and distributed systems where IDs must be generated without central coordination.
What makes UUID v4 different from other versions?
Version 4 UUIDs are generated entirely from random bytes. Other versions use time-based (v1, v7), name-based using MD5 or SHA-1 (v3, v5), or MAC address algorithms. V4 is the most widely used because it requires no coordination — just random data from a secure source.
Are the generated UUIDs truly unique?
In practice, yes. UUID v4 has 122 bits of randomness. The probability of generating two identical values is approximately 1 in 5.3 × 10³⁶ — so small that collisions are not a realistic concern for any application.
Is this generator cryptographically secure?
Yes. The tool uses crypto.randomUUID() from the browser's Web Crypto API, which draws entropy from your operating system's CSPRNG — the same source used for TLS key generation. All values are generated locally; nothing is sent to any server.