UUID Generator
Generate unique identifiers (UUID v4)
About UUID Generator
Creates version 4 UUIDs in the standard lowercase 8-4-4-4-12 format, with 122 of the 128 bits random and the rest marking the version and variant. Generate one, five or ten per click, copy any single value, or use Copy all to grab them as a newline-separated list. Handy for seeding databases, mocking API responses and building test fixtures.
Category: Generators.
Frequently asked questions
What is a UUID/GUID?
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A Universally Unique Identifier (UUID) is a 128-bit number formatted as 8-4-4-4-12 hexadecimal digits (e.g., 550e8400-e29b-41d4-a716-446655440000). GUID is Microsoft's name for the same standard.
Which UUID version does this tool generate?
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Only version 4, the random one. Version 1 embeds a timestamp and the machine's MAC address, and version 7 (RFC 9562) starts with a Unix timestamp so values sort by creation time, which suits database keys; neither is offered here.
Can two UUIDs ever be the same?
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In theory yes, but there are 2^122 (about 5.3 × 10^36) possible v4 values, so you would need to generate roughly 103 trillion of them for a one-in-a-billion chance of a duplicate. That estimate assumes a high-quality random source.
Can I use these UUIDs as secret tokens?
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No. This tool builds UUIDs with Math.random(), which is fast but not cryptographically secure, so values could be predictable. For session IDs, API keys or password-reset links, generate them in your code with crypto.randomUUID() or another CSPRNG.