UUID Generator
Random v4 and time-ordered v7 UUIDs, in bulk — plus a UUID inspector.
Generate UUIDs
Special UUIDs
- Nil UUID
00000000-0000-0000-0000-000000000000 - Max UUID
ffffffff-ffff-ffff-ffff-ffffffffffff
Validate & inspect
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About the UUID Generator
Create UUIDs (also called GUIDs) for database keys, API resources, test data and file names. Version 4 UUIDs are 122 random bits from your browser's cryptographically secure random number generator. Version 7 UUIDs start with the current Unix time in milliseconds, so they sort in creation order — which keeps database indexes compact and fast. Both follow RFC 9562, the 2024 standard that replaced RFC 4122.
Generate one or up to 1,000 at a time, in lowercase or uppercase, with or without hyphens, or in Microsoft-style braces. The Validate & inspect box checks any UUID (or a whole list) and shows its version and variant — and, for versions 1, 6 and 7, the exact moment it was created.
How to use it
- Choose v4 (random) or v7 (time-ordered). A fresh UUID appears straight away.
- Set How many (up to 1,000) and press Generate — or Enter in the number box.
- Pick the format: uppercase, hyphens and braces. The list updates without generating new values.
- Use Copy or Download .txt. To check a UUID, paste it (or several, one per line) into Validate & inspect.
Examples
919108f7-52d1-4320-9bac-f847db4148a8
The 13th hex digit is always 4 (the version) and the 17th is 8, 9, a or b (the variant).
017f22e2-79b0-7cc3-98c4-dc0c0c07398f
Version 7 · created 2022-02-22T19:22:22.000Z (Unix time 1,645,557,742,000 ms)
This is the example from RFC 9562 Appendix A.6.
Standard: 017f22e2-79b0-7cc3-98c4-dc0c0c07398f
No hyphens: 017f22e279b07cc398c4dc0c0c07398f
Braces (upper case): {017F22E2-79B0-7CC3-98C4-DC0C0C07398F}Common uses
- Primary keys that can be created by the client or by several servers without coordination.
- Time-sortable IDs (v7) for event logs, message queues and database tables with heavy inserts.
- Test fixtures, seed data and mock API responses that need many unique IDs.
- Correlation and idempotency keys for API requests.
- Checking whether a value from a log or database is a valid UUID, and when a v1/v6/v7 UUID was made.
v4 or v7?
v4 is the safe default when an ID should reveal nothing: all 122 non-fixed bits are random. Random keys are spread across a database index, which costs some write performance in very large tables.
v7 puts a 48-bit millisecond timestamp first and fills the remaining 74 bits with random data, so new IDs land at the end of a B-tree index; RFC 9562 recommends v7 over the older time-based versions 1 and 6. UUIDs generated here in the same millisecond are still strictly increasing (the random part is incremented, as RFC 9562 §6.2 describes). The trade-off: anyone who sees a v7 UUID can read when it was created.
How unique are they?
With 122 random bits, you would need to generate about 2.7 × 10^18 (2.7 quintillion) v4 UUIDs before the chance of even one duplicate reaches 50%. In practice, collisions come from broken random number generators, not from the format — which is why this page only uses crypto.getRandomValues, the browser's cryptographically secure generator.
UUIDs are identifiers, not secrets. Do not use them as passwords, API keys or session tokens; use the Password Generator for secrets.
Limitations
- Up to 1,000 UUIDs per batch. Generate again for more — v7 values keep increasing across batches.
- Versions 1, 3, 5, 6 and 8 can be inspected but not generated here.
- The inspector reads the time from v1, v6 and v7 UUIDs; v2 UUIDs do not contain a complete timestamp.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
Is a GUID the same as a UUID?
Yes. GUID is Microsoft's name for the same 128-bit format. Windows tools often show it in upper case inside braces, e.g. {919108F7-52D1-4320-9BAC-F847DB4148A8} — choose Uppercase and Braces to get that format.
Are these UUIDs generated on a server?
No. They are generated in your browser with its secure random number generator. Nothing is sent anywhere, and the page works offline once loaded.
Can two people get the same UUID?
For v4, the chance is so small that it can be ignored: 122 random bits give more than 5 × 10^36 possible values. v7 UUIDs created on different devices in the same millisecond are still told apart by their 74 random bits.
What are the nil and max UUIDs?
Two special values defined by RFC 9562: the nil UUID 00000000-0000-0000-0000-000000000000 means "no value", and the max UUID ffffffff-ffff-ffff-ffff-ffffffffffff is used as a sentinel, for example as an upper bound in ranges.
Why does my UUID fail validation?
A UUID has exactly 32 hex digits (0–9, a–f), usually grouped 8-4-4-4-12 with hyphens. The checker tells you what is wrong — a wrong length, an invalid character, or hyphens in the wrong place — and flags values that have the right shape but are not standard RFC 9562 UUIDs.