UUIDv4 Generator

Generate random UUIDv4 identifiers with the browser’s secure random source and copy them immediately.

Single UUIDs and batch files are generated locally with the browser Web Crypto API.

Single UUIDs and batch files are generated locally with the browser Web Crypto API.

Current UUIDv4

Download UUIDv4 batch

Choose between 1 and 100,000. One lowercase UUID is written per line.

What this tool does

Create RFC 9562 UUID version 4 identifiers from cryptographically secure random values.

Copy one UUID or create a local text file containing a larger batch.

How to use the tool

  1. Use the UUID shown in the first panel or generate another one.
  2. Copy the current value when you need a single identifier.
  3. Choose a whole-number batch size from 1 to 100,000.
  4. Generate the text file; it contains one lowercase UUID per line.

Useful applications

  • Create identifiers for database rows, API resources, fixtures, and test data.
  • Prepare independent IDs in distributed systems without coordinating a central counter.
  • Produce sample UUIDs for documentation, demonstrations, or automated tests.
  • Generate a newline-separated import file for development or migration work.

Notes and limitations

  • UUIDv4 is a 128-bit UUID with 122 random bits; version and variant occupy the other six bits.
  • The fourth hexadecimal group starts with 8, 9, a, or b, and the version digit is always 4.
  • UUIDv4 values are not time ordered and should not be treated as passwords, access tokens, or proof of authenticity.
  • Generation and batch-file creation run locally in the browser and do not send UUIDs to petuja.tools.

Frequently asked questions

How is UUIDv4 generated?

The browser uses crypto.randomUUID() or crypto.getRandomValues(), then sets the RFC 9562 version and variant bits.

Can two UUIDv4 values collide?

A collision is theoretically possible, but with 122 random bits it is extraordinarily unlikely for ordinary workloads.

Does UUIDv4 contain a timestamp or device address?

No. Version 4 is random-based and does not encode a timestamp, MAC address, or sortable creation time.

Can I use UUIDv4 as a password or session token?

Not automatically. A UUID identifies an object; security-sensitive tokens need application-specific threat analysis and controls.

Are generated UUIDs uploaded?

No. The displayed UUID and the downloaded batch are generated locally in your browser.

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