UUID Generator
Generate v1, v3, v4, and v5 UUIDs locally in your browser.
UUID Version
Generated UUIDs
Unique within this generated batch.
Adjust the count or version to generate UUIDs.
What Is a UUID?
A UUID, also called a GUID in some systems, is a 128-bit identifier formatted as five hexadecimal groups. UUIDs are commonly used for database records, distributed systems, file names, event ids, and API objects where a unique value is useful without coordinating with a central counter.
UUID Versions
| Version | Type | Best for |
|---|---|---|
| v1 | Time based | Ordered identifiers where timestamp information is acceptable. |
| v3 | Namespace plus name, MD5 | Deterministic identifiers for legacy systems that require v3. |
| v4 | Random | Most application ids, tokens, records, and general developer use. |
| v5 | Namespace plus name, SHA-1 | Deterministic identifiers when the same input should produce the same UUID. |
About Uniqueness
Version 4 UUIDs are designed to be practically unique through randomness, not by checking every UUID ever created. This tool de-duplicates each v1/v4 batch before displaying it, so the generated list itself will not contain duplicates. Versions 3 and 5 are different: they are deterministic, which means the same namespace and name intentionally produce the same UUID.
Namespace-Based UUIDs
Versions 3 and 5 are deterministic. If you use the same namespace UUID and the same name, you get the same result every time.
RFC presets (DNS, URL, OID, X.500) use fixed standard namespace UUIDs. New custom creates a random namespace for your own project.
Practical Tips
- Use v4 when you simply need a unique identifier.
- Use v5 when the id must be repeatable from the same namespace and name.
- Avoid v1 if timestamp leakage is a concern.
Frequently Asked Questions
Use v4 for most application identifiers. Use v3 or v5 when you need the same namespace and name to always produce the same UUID.
v4 UUIDs are random and practically unique, but any random identifier is probabilistic. This tool also de-duplicates each generated v1/v4 batch. v3 and v5 are deterministic, so the same namespace and name intentionally produce the same UUID.
Yes. v1 and v4 support bulk generation up to 1000 UUIDs. v3 and v5 are deterministic and produce one UUID per namespace and name.