UUID Generator (v4 and v1)
Generate random UUID v4 or time-based v1 identifiers, up to 100 at once, in standard, uppercase, no-hyphen, braces or URN format. Validate any UUID.
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About this tool
A UUID (Universally Unique Identifier, called a GUID in the Microsoft world) is a 128-bit ID written as 32 hexadecimal digits in five groups, like 550e8400-e29b-41d4-a716-446655440000. This UUID generator creates them instantly in your browser: one or up to 100 at a time, as version 4 (random) or version 1 (time-based), in the format your code or database expects.
How to generate UUIDs
- Choose the version: v4 for random IDs (the usual choice) or v1 for time-based IDs.
- Set how many you need, from 1 to 100.
- Pick the output format: standard lowercase, uppercase, without hyphens, wrapped in braces, or as a URN (urn:uuid:...).
- Copy a single UUID, copy them all, or download the list as a text file. A list or grid view makes long batches easy to read.
UUID v4 or v1?
- Version 4 is built from 122 random bits. The chance of two v4 UUIDs ever colliding is so small that you can create them on any machine without coordination. Use it for database keys, API tokens, file names and request IDs.
- Version 1 combines a timestamp with a node identifier, so IDs created later sort after earlier ones. The tool shows the timestamp hidden in each v1 UUID. Because v1 reveals when it was made, prefer v4 for anything public.
Output formats
| Format | Example |
|---|---|
| Standard | 550e8400-e29b-41d4-a716-446655440000 |
| Uppercase | 550E8400-E29B-41D4-A716-446655440000 |
| No hyphens | 550e8400e29b41d4a716446655440000 |
| Braces | {550e8400-e29b-41d4-a716-446655440000} |
| URN | urn:uuid:550e8400-e29b-41d4-a716-446655440000 |
Validate a UUID
Paste any UUID into the validator to check that it is well formed and see which version it is. That is useful when an API rejects an ID or you inherit data from another system.
Where UUIDs are used
Primary keys in distributed databases, object IDs in APIs, idempotency keys for payments, unique file and upload names, and correlation IDs in logs.
Frequently asked questions
What is the difference between a UUID and a GUID?
They are the same thing. GUID is Microsoft's name for a UUID; both are 128-bit identifiers written as 32 hexadecimal digits.
Can two UUID v4 values ever be the same?
In theory yes, in practice no. A v4 UUID has 122 random bits, so you would need to generate billions of IDs per second for many years before a collision became likely.
Which UUID version should I use?
Use version 4 in almost every case. Use version 1 only when you need IDs that sort by creation time and it is fine to reveal when they were made.
How many UUIDs can I generate at once?
Up to 100 per batch. You can copy them all at once or download them as a text file.
Are the UUIDs generated on a server?
No. They are generated in your browser, so they are not logged or stored anywhere.
How do I check whether a string is a valid UUID?
Paste it into the UUID validation box. The tool tells you whether it is valid and which version it is.