UUID v4 Generator (RFC 4122, Batch)

Generate secure, random UUID v4 identifiers in your browser. Private by design—nothing leaves your device.

Controls

Ready.

Output

Tip: Press Ctrl/Cmd + Enter to regenerate with the same settings.

Legend (hyphenated view):
XXXXXXXX = time_low
XXXX = time_mid
4XXX = time_hi_and_version
XX XX = clock_seq (variant in high bits)
XXXXXXXXXXXX = node

Understanding UUID v4

A UUID v4 generator creates unique identifiers that are safe to use in databases, APIs, and software projects. A UUID (Universally Unique Identifier) is a 128‑bit value formatted as a 36‑character string with hyphens, like xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. Version 4 UUIDs are based on random numbers, which makes collisions extraordinarily unlikely in normal use.

This tool is ideal when you need an ID that will not clash with others across systems, teams, or services. Common uses include primary keys in databases, document IDs in JSON APIs, session identifiers, and unique filenames. Because UUIDs do not rely on timestamps or device information, they are also a good choice when you want identifiers that are difficult to guess.

How UUID v4 works

A UUID v4 is 16 bytes (128 bits) long. Most of those bits are random, while a few are reserved to mark the version and variant. The “4” in the third group indicates version 4, and the first two bits of the next group set the RFC 4122 variant. The rest is random, which is what gives UUID v4 its strength.

  • Uniqueness: 122 random bits make collisions astronomically unlikely.
  • Randomness: No timestamps or MAC addresses are embedded.
  • Interoperability: Supported across languages, frameworks, and databases.

How to use this generator

  1. Choose how many UUIDs you want to create.
  2. Select the output format (hyphenated or compact) if available.
  3. Click Generate to produce a new list of UUID v4 values.
  4. Copy the IDs into your app, database, or configuration file.

Under the hood, the generator uses your browser’s secure random number source via crypto.getRandomValues(). It produces 16 random bytes, then sets the version and variant bits to follow the UUID v4 standard. Everything runs locally in your browser, so no data leaves your device.

UUID v4 structure

In the hyphenated view, the color legend highlights the five sections of a UUID:

  • time_low: 8 hex digits (red)
  • time_mid: 4 hex digits (green)
  • time_hi_and_version: starts with 4 (blue)
  • clock_seq: 4 hex digits (gold)
  • node: 12 hex digits (purple)

If you are comparing ID formats, UUID v4 is a reliable default: readable, widely supported, and safe for distributed systems. Use it whenever you need identifiers that won’t collide, even across multiple servers or apps.

5 Fun Facts about UUID v4s

122 bits of chaos

Only 6 of the 128 bits are reserved, so v4 leaves 2122 (~5.3×1036) possibilities—more identifiers than grains of sand on Earth.

Collision odds

Birthday paradox hero

You could mint 1 million UUIDs every second for 68 years before the 50/50 chance of a collision kicks in. That is 2.1×1015 identifiers.

Mind-boggling scale

Entropy under the hood

This tool taps crypto.getRandomValues(), which pulls from your OS’s secure RNG (keyboard jitter, clock drift, hardware noise)—not Math.random().

True randomness

Version handshake

The blue nibble is forced to 4 and the next byte starts with 10. Those locked bits let every language instantly recognise a v4 + RFC variant.

Interop signal

Burst-friendly batches

Generate up to 200 IDs at once, colour-check them in the preview, then copy or download in one click—handy for staging databases and API fixtures.

Productivity boost

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