Development
UUID Generator
Generate UUIDs according to RFC 9562 – random (v4), time-sortable (v7), classic (v1) or from a name (v5/v3). One at a time or up to 1,000 at once, as a list, JSON or SQL. Plus: check and decode any UUID.
- Runs entirely in your browser
- No data upload
- No sign-up
- Free
Generate UUIDs
Cryptographically secure randomnessTip: Space generates new UUIDs when no input field is active.
Check & decode a UUID
Guide
How it works
- Choose a version
If in doubt, v4 – or v7 if the IDs serve as database keys and should sort by time. v5 and v3 always produce the same UUID from a name.
- Set the count
A single UUID or up to 1,000 at once. With v5/v3, each line in the name field results in one UUID.
- Adjust the notation
Upper or lower case, with or without hyphens, in braces like Microsoft GUIDs or as urn:uuid:. Lists are available line by line, comma-separated, as a JSON array or as an SQL IN list.
- Use or check
Copy, download or press the space bar to generate new UUIDs. Below you can check any UUID – including its version and contained timestamp.
FAQ
Frequently asked questions
What is a UUID?
A UUID (Universally Unique Identifier, called GUID by Microsoft) is a 128-bit identifier written as 32 hex characters in the form 8-4-4-4-12. It can be generated without a central authority and is still practically unique worldwide.
Which version should I use?
v4 for almost everything. v7 if the IDs are primary keys in a database: because they start with the time, new entries are appended at the end, which keeps indexes fast. v5 if the same name should always produce the same ID. v1 and v3 only for older systems.
Can two UUIDs be the same?
Theoretically yes, practically no: a v4 UUID has 122 random bits. Even at one billion UUIDs per second you would have to wait about 85 years until the probability of a single duplicate reaches 50%.
Are the UUIDs securely random?
Yes. The tool uses crypto.getRandomValues() – your browser’s cryptographically secure random number generator, not Math.random(). UUIDs are still not passwords or secret tokens: they are designed to be unique, not secret.
Does a UUID reveal anything about me?
v1 UUIDs used to contain the computer’s MAC address and the exact time. This tool uses a random node instead of the MAC address for v1. However, v1, v6 and v7 always contain the time of generation – the check below shows it.
Are the UUIDs stored anywhere?
No. Everything happens locally in your browser; the server learns nothing about the generated or checked UUIDs.