UUID Generator

About the UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by the Open Software Foundation and widely adopted across databases, distributed systems, and public APIs. Unlike a sequence number, a UUID can be generated on any machine, at any time, without coordination with a central authority, and the odds of two generated values colliding are so small that they are treated as unique for all practical purposes.

This generator produces UUID version 4 values, which derive their uniqueness from randomness. 122 of the 128 bits are randomly chosen, meaning the probability of generating the same UUID twice is approximately one in 5.3 × 10³⁶ — a number so large that even generating a trillion UUIDs per second for a hundred years would not exhaust the space.

Everything happens locally in your browser using the Web Crypto API, the same cryptographic randomness browsers use for secure connections. Your UUIDs are never sent to a server, so they remain safe to use in production systems, API keys, or any other sensitive context.

How to use the UUID Generator

1. 1 Choose how many UUIDs you need using the quantity selector — one, or a bulk batch of up to a few hundred at a time.
2. 2 Click Generate. A new set of UUIDs appears instantly; each value is fresh, random, and unrelated to previous batches.
3. 3 Copy a single UUID with its copy button, or copy the entire batch at once for pasting into seed files, fixtures, or spreadsheets.
4. 4 Generate again whenever you need more. There is no rate limit because the generation happens entirely on your device.

Key features

Who uses the UUID Generator?

• Primary keys in databases where you want to merge data from multiple sources without key conflicts.
• Correlation and trace IDs in distributed systems, log entries, and message queues so a request can be followed across services.
• File and object names in cloud storage (S3 keys, blob names) that must never collide between users.
• Identifiers in public APIs and URLs where sequential integers would leak business volume or enable enumeration attacks.
• Test fixtures and development seeds where realistic-looking, non-repeating IDs save manual editing.
• License keys, session tokens, and nonce values where unpredictable uniqueness matters.

Tips and best practices

• Prefer UUIDv4 for general purposes; UUIDv1 embeds the MAC address and timestamp, which can leak information about the generating machine.
• Do not trim or normalize the hyphens — most parsers expect the canonical 8-4-4-4-12 hexadecimal format.
• Store UUIDs in their native 16-byte binary column type (for example BINARY(16) in MySQL) rather than as text when tables grow large; it is smaller and indexes faster.
• If your database supports it, use the built-in UUID column type (PostgreSQL) or the UUID_TO_BIN helper (MySQL 8) for best index performance.
• For very high insert volumes where index page splits hurt performance, consider ULIDs or UUIDv7 which sort naturally by time — but for typical use, v4 is the safe standard.
• Never treat a UUID as a secret. It is unique, not confidential; protect access with authentication, not obscurity.

Frequently asked questions