Skip to main content

UUID Generator

Loading…

About UUID Generator

The UUID Generator creates random UUID v4 (Universally Unique Identifier) strings instantly. Generate one or hundreds of UUIDs at once. Perfect for database primary keys, API tokens, session identifiers, test data, and any use case requiring globally unique identifiers.

UUID v4 generates its 128 bits almost entirely from random data, giving an astronomically low collision probability: you would need to generate over a trillion UUIDs per second for billions of years to have a 50% chance of a single collision.

Generated UUIDs follow the canonical format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where 4 indicates version 4 and y is one of 8, 9, a, or b.

All UUIDs are generated using the browser's cryptographically secure random number generator (crypto.randomUUID or crypto.getRandomValues). Your data never leaves your device.

Practical Uses for UUID Generator

  • Generate a primary key for a new database table
  • Create a unique session ID for a web application
  • Generate test data IDs for a QA fixture
  • Create a unique file name to avoid collisions during upload
  • Generate an idempotency key for a payment API request
  • Create unique tracking IDs for a distributed system's log entries

How to Use UUID Generator

  1. Click Generate to create a UUID.

  2. Increase the count to generate multiple UUIDs at once (up to 100).

  3. Choose uppercase or lowercase output format.

  4. Copy the result.

Examples

Example — Single UUID
Input
(click Generate)
Output
550e8400-e29b-41d4-a716-446655440000
Example — Bulk generate for test fixtures
Input
(click Generate, count: 3)
Output
e4eaaaf2-d142-11e1-b3e4-080027620cdd
3f2504e0-4f89-11d3-9a0c-0305e82c3301
6ba7b810-9dad-11d1-80b4-00c04fd430c8

Who Uses the UUID Generator Tool

  • Backend developers generate primary keys and unique identifiers for database records and distributed systems.
  • QA engineers create batches of unique test data IDs for fixtures and mock records.
  • DevOps engineers generate unique identifiers for infrastructure resources, deployments, or trace IDs.
  • API developers create idempotency keys to safely retry payment or transaction requests.
  • Students learn how UUIDs guarantee uniqueness across distributed systems.

Comparisons

UUID vs Auto-Increment ID

Auto-increment integer IDs (1, 2, 3...) are simple and compact, but they require a single, centrally coordinated counter — which becomes a bottleneck or conflict risk in distributed systems with multiple databases or services generating IDs independently. They also reveal information, like roughly how many records exist.

UUIDs can be generated independently by any client or server with virtually zero chance of collision, making them ideal for distributed systems, offline-first apps, and merging data from multiple sources. The tradeoff is size (36 characters vs. a few digits) and, for UUID v4, no inherent ordering — UUID v7 addresses that by embedding a sortable timestamp.

Frequently Asked Questions

What is UUID v4?

UUID v4 is a randomly generated 128-bit identifier standardized in RFC 4122. It is represented as 32 hexadecimal characters in the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx.

What is the difference between UUID and GUID?

They are the same thing. UUID (Universally Unique Identifier) is the standard term; GUID (Globally Unique Identifier) is Microsoft's term for the same concept.

Are the UUIDs cryptographically random?

Yes — crypto.randomUUID() or crypto.getRandomValues() is used, providing cryptographically strong randomness.

Can two generated UUIDs ever be the same?

Theoretically yes, but the probability is negligible. With UUID v4, the chance of collision is 1 in 2^122 per pair. You would need to generate quintillions of UUIDs to approach a 1% collision probability.

What is the difference between UUID v1, v4, and v7?

v1 is based on the machine's MAC address and timestamp (not recommended for privacy reasons). v4 is randomly generated. v7 is the newest standard — it encodes a millisecond timestamp for sortability while keeping most bits random.

Can I use UUIDs as database primary keys?

Yes — UUIDs are widely used as primary keys, especially in distributed systems where auto-increment integers would require centralized coordination. UUID v7 is better for database primary keys as its time-based prefix maintains insert order.

Can I generate UUID v7 for sortable database keys?

This tool generates UUID v4 (fully random). If your database specifically needs UUID v7 for time-ordered sortability, use a library that implements the v7 spec, though v4 remains the most widely supported version.

Is it safe to use a UUID as a public identifier in a URL?

Yes — UUIDs are commonly used in URLs since they're unguessable and don't leak sequential information the way auto-increment IDs do.

How many UUIDs can I generate at once?

Up to 100 in a single click, which covers most bulk test-data or fixture-generation needs. For larger batches, generate multiple times.