UUID Generator & Validator
Generate cryptographically secure UUIDs, validate any UUID string, and decode v1 timestamps — all in your browser.
About UUIDs
A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify
objects in computer systems — database rows, API resources, session tokens, file IDs.
The standard text representation is 32 hexadecimal characters grouped by hyphens:
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
The letter M encodes the version (1–5) and the two high bits of the N byte encode the variant. Together they tell you how the UUID was generated and what rules it follows.
UUID v4 is the most widely used version. All 122 non-fixed bits are randomly generated using a cryptographically secure PRNG. The probability of two v4 UUIDs colliding is vanishingly small — roughly 1 in 5.3 × 10³⁶.
UUID v1 encodes a timestamp (100-nanosecond intervals since 15 October 1582) and the generating machine's MAC address. It is globally unique and time-sortable, but leaks hardware information — which is why v4 replaced it for most applications.
UUID v3 and v5 are namespace-based: they hash a namespace UUID and a name to produce a deterministic UUID. Same inputs always produce the same UUID. v3 uses MD5; v5 uses SHA-1. v5 is preferred.
Frequently Asked Questions
Is this UUID generator cryptographically secure?
Yes. uuidchop uses crypto.randomUUID() from the browser's Web Crypto API, which generates cryptographically secure random bytes — the same source used by operating systems and security libraries.
Are my UUIDs sent to a server?
No. All generation and validation runs entirely in your browser. Nothing is transmitted. The page functions offline after its initial load.
What's the difference between UUID v1 and v4?
v1 encodes a timestamp and MAC address — time-sortable but leaks hardware info. v4 is purely random — no timestamp, no MAC, no privacy concern. Use v4 unless you specifically need v1's sortability.
How many UUIDs can I generate at once?
Up to 100 at a time in the browser. Need thousands? The crypto.randomUUID() API is available in all modern environments — use it directly in Node.js, Deno, or browser scripts.
What UUID formats does the validator accept?
Standard hyphenated format (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx), compact 32-char hex without hyphens, and uppercase variants. The validator normalises the input before checking.
Can I use uuidchop from an AI agent or script?
Yes — see AGENTS.md for the machine-readable capability description and planned API endpoint.