UUID Generator

1. Set How many? to the number of UUIDs you need (1–10,000).
2. Pick a Format: default lowercase with hyphens, uppercase, no hyphens (32 hex chars), wrapped in braces, or as a URN.
3. Click Generate. The UUIDs appear in the output box, one per line.
4. Use Copy all to copy them to your clipboard, or .txt to download.

This generator uses the browser's native crypto.randomUUID() function, which is implemented using the operating system's cryptographically secure random number generator (CSPRNG). Every UUID is generated locally on your device — there is no network request, no server-side entropy pool, and no possibility of collision with another user's UUIDs.

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier) in Microsoft ecosystems, is a 128-bit identifier defined in RFC 4122. The standard textual representation is 32 hexadecimal digits grouped into five sections separated by hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx. The total number of possible v4 UUIDs is 2¹²² — roughly 5.3 × 10³⁶, which means collisions are astronomically unlikely even at planetary scale.

UUIDs are used as database primary keys (especially in distributed systems where auto-increment integers cause conflicts), as request IDs in microservice architectures, as session tokens, as object identifiers in file systems and content-addressable storage, and in countless other places that need a unique identifier without coordinating with a central authority.

RFC 4122 defines five versions:

• v1 — time-based, derived from the current time and the machine's MAC address. Sortable but leaks the MAC address.
• v2 — DCE Security version, with embedded POSIX UIDs. Rarely used.
• v3 — namespace + name + MD5 hash. Deterministic — the same inputs always produce the same UUID.
• v4 — random. The most common version. This tool generates v4.
• v5 — same as v3 but using SHA-1 instead of MD5. Preferred over v3 for new systems.

There are also newer non-RFC versions: v6 (time-ordered, sortable like ULID), v7 (time-ordered with millisecond timestamp prefix), and v8 (vendor-defined). Most modern systems use v4 or v7.

Yes. crypto.randomUUID() uses the same CSPRNG that powers crypto.getRandomValues(), which on modern browsers and operating systems draws from /dev/urandom on Linux, the CryptGenRandom API on Windows, and the SecRandomCopyBytes API on macOS. The output is suitable for use as session tokens, CSRF tokens, or any other security-sensitive identifier.

For all practical purposes, yes. The probability of two randomly-generated v4 UUIDs colliding is approximately 1 in 2.7 × 10¹⁷ after generating 100 trillion UUIDs. To put that in perspective: if you generated one billion UUIDs per second for 100 years, the chance of a collision would still be effectively zero.

No. UUIDs are generated locally in your browser using native APIs. No network request is made. There is nothing to intercept or log.