UUID Generator
Generate random UUIDs (v4). Free, no signup, runs in your browser.
How It Works
Choose how many UUIDs you need and click Generate. Each UUID is a version 4 random identifier generated using your browser's cryptographic API. Click Copy to copy all UUIDs to your clipboard.
What Is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier in the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. Version 4 UUIDs are randomly generated and have an astronomically low probability of collision, making them safe for database keys, session tokens, and distributed systems.
Anatomy of a Version 4 UUID
| Segment | Length | Meaning |
|---|---|---|
| xxxxxxxx | 8 hex digits | Random |
| xxxx | 4 hex digits | Random |
| 4xxx | 4 hex digits | Version (starts with 4) |
| yxxx | 4 hex digits | Variant (y is 8, 9, a or b) |
| xxxxxxxxxxxx | 12 hex digits | Random |
Common Uses
UUIDs are used as primary keys in databases, as identifiers for records created across multiple services, for session and request tracing, in file and object names to avoid clashes, as idempotency keys for API calls, and for seeding test and sample data. Because a version 4 UUID is generated from random bits, separate systems can create IDs independently without ever coordinating and still avoid duplicates.
Frequently Asked Questions
How do I generate a UUID?
Set how many you need and click Generate. The UUIDs appear in the output box, one per line, and the Copy all button puts the whole list on your clipboard.
How many UUIDs can I generate at once?
Between 1 and 1000 at a time. Enter the count in the How many field and each click produces that many fresh, unique version 4 UUIDs, one per line, so you can create a batch for seeding a database or test data in seconds.
Are these UUIDs cryptographically secure and random?
Yes. Each UUID is created with the browser's crypto.randomUUID function, which draws on a cryptographically secure random source. They are version 4 UUIDs with 122 random bits, giving an astronomically low chance of two ever colliding.
What is the format of the UUIDs?
They follow the standard version 4 layout xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx: 32 hexadecimal digits in five hyphen-separated groups, with a 4 marking the version and the y digit indicating the variant. Output is lowercase.
Is a UUID the same as a GUID?
Yes, in practice. GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit identifier. The UUIDs this tool produces are valid GUIDs, and everything is generated locally in your browser with nothing sent to a server.