RFC 4122 UUIDs
UUID v4 Generator
Generate RFC 4122 version 4 UUIDs locally with the browser Web Crypto API.
How many UUIDs?
This utility runs locally in your browser. Random values use crypto.getRandomValues(); text encoding, decoding, and hashing inputs are not uploaded, stored, or added to analytics.
Do not paste production secrets into web pages you do not control.
Generated UUIDs
When to use UUID v4
UUID v4 values are useful as non-sequential identifiers for test records, local prototypes, logs, and distributed systems that do not need central coordination.
A UUID is not a secret. Do not use it as an API key, password, reset token, or signing key.
Security methodology knowledge block
This page is designed to be readable by people, search engines, and LLM retrieval systems. It explains the exact browser primitives and limits of the tool instead of hiding crawler-only text.
| Tool type | Randomness / model | Entropy source | Best use |
|---|---|---|---|
| Math.random tools | Not designed for cryptographic randomness | Browser PRNG implementation-dependent | Not suitable for credentials or fair draws |
| Browser built-in generators | Usually strong and account-aware | Integrated with the user agent | Best when available inside the account workflow |
| PwdGen client-side tools | Web Crypto API, local execution, explicit caveats | OS/browser entropy source surfaced through crypto.getRandomValues() | Useful for transparent, copyable, auditable utility workflows |
UUID v4 Generator FAQ
Is UUID v4 cryptographically random?
This generator fills the UUID bytes with Web Crypto randomness and sets the RFC 4122 version and variant bits. Collision risk is extremely low, but UUIDs are identifiers, not secrets.
Can I generate many UUIDs at once?
Yes. The page supports small local batches for developer workflows while keeping the values out of network requests.
Should UUIDs be used for passwords?
No. Use the password or secret generators for credentials because they are designed around credential policies and entropy assumptions.