UUID / GUID Generator (v4)
Generate RFC 4122 version 4 UUIDs in bulk using the browser's cryptographic random source. Useful whenever you need identifiers that are unique without coordinating with a central database: test fixtures, primary keys, correlation IDs and idempotency keys.
How it works
- 1
Choose how many UUIDs you need in one batch.
- 2
Generate — each value comes from crypto.randomUUID(), falling back to the Web Crypto RNG on older browsers.
- 3
Review the list; every value is a standard 36-character version 4 UUID.
- 4
Copy the whole batch and paste it into your code, seed data or spreadsheet.
What people use it for
- Seeding a database or test fixture with realistic primary keys.
- Creating correlation or request IDs for tracing a distributed system.
- Generating idempotency keys for payment or webhook retries.
- Naming files, uploads or storage objects without collisions.
Supported formats & options
| Version | UUID version 4 (random), RFC 4122 variant |
|---|---|
| Output format | Canonical lowercase hyphenated form, e.g. 3f2a9c1e-8b7d-4c6a-9f10-2b5c8e4d7a13 |
| Randomness source | crypto.randomUUID(), falling back to crypto.getRandomValues() |
Key advantages & benefits
Genuinely random, version 4
Values use the platform's cryptographic generator, so they carry the collision properties a v4 UUID is supposed to have.
Bulk output
Generate an entire batch at once instead of refreshing a page for each identifier.
Standard formatting
Output uses the canonical hyphenated 8-4-4-4-12 form accepted by Postgres uuid columns, JSON APIs and language UUID parsers.
Copy the whole set
One click copies every generated value, newline-separated and ready to paste.
Limits & things to know
- Version 4 UUIDs are random, not sortable. If you need identifiers that sort by creation time, use a time-ordered scheme such as UUIDv7 or ULID.
- 128-bit random identifiers index less compactly than integers — a deliberate trade for decentralised uniqueness, not a defect.
- The tool generates identifiers; it cannot check them against your database for values already in use.
Troubleshooting
Nothing is generated on an older browser
crypto.randomUUID() needs a recent browser and a secure context. The tool falls back to crypto.getRandomValues(); a browser with neither cannot generate securely, so update it rather than accept a weaker source.
The database rejects the value
Some systems expect UUIDs without hyphens, or wrapped in braces. Strip or add those to match the format your column uses.
Privacy & data handling
Identifiers are generated locally and never transmitted. Because they are random rather than derived from your device, they contain no information about you or your machine.
UUID Generator — Create Random UUID v4 Online
Generate random UUID v4 identifiers instantly, one at a time or in bulk. A free online UUID generator for database primary keys, API request IDs, idempotency keys, test fixtures and anywhere else you need a value that will not collide.
- Standards-compliant UUID v4 — 128-bit random identifiers in the canonical 8-4-4-4-12 hyphenated form, exactly as RFC 4122 specifies.
- Cryptographically strong randomness — generated with the browser's Web Crypto API, so collisions remain a theoretical rather than a practical concern.
- Bulk generation — produce a full list in one click for seeding a database, populating test fixtures or pre-allocating record IDs.
- Copy-ready output — grab one identifier or the whole batch to the clipboard without reformatting.
- Generated on your device — identifiers are created locally in your browser, so nothing about your data model is exposed to a third party.
Free with no limit. Use the Password Generator for secrets — a UUID is unique, not secret — and the Hash Generator for content fingerprints.
Frequently asked questions
What is the probability of a UUID collision?
The probability is virtually zero (1 in 2^122), making UUIDs globally unique.
Are these UUIDs safe to use as database keys?
Yes. They are version 4 UUIDs generated from the browser's cryptographic random source, so collisions are not a practical concern. Bear in mind that random UUIDs do not sort by creation time and index less compactly than integers.
What is the difference between UUID v4 and v7?
Version 4 is entirely random. Version 7 embeds a timestamp so identifiers sort chronologically, which helps database index locality. This tool generates v4; if insert ordering matters for your workload, use a v7 or ULID library instead.
Can two people generate the same UUID?
In practice, no. A v4 UUID has 122 random bits, so the probability of a collision is negligible even across billions of values — that is the entire point of the format.
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