Developer / TOOLKIT
UUID v4 Generator
Create 1–500 random version 4 identifiers, then copy the batch or download it as TXT. Choose uppercase or remove hyphens to match your receiving system.
Free to use · No account needed
Generate a batch in three steps
- Choose a count from 1 to 500 and the format options.
- Select Generate UUIDs. Changing the count or an option also generates a fresh batch.
- Copy one value, use Copy all, or download uuids.txt. Keep that file if you need to reuse the same fixture values.
Format example: the same identifier in three forms
This fixed example explains formatting; it is not a fresh ID and should not be reused for new records.
| Option | Example |
|---|---|
| Default | 550e8400-e29b-41d4-a716-446655440000 |
| Uppercase | 550E8400-E29B-41D4-A716-446655440000 |
| No hyphens | 550e8400e29b41d4a716446655440000 |
Hyphens give the usual 36-character representation; removing them leaves 32 hexadecimal characters. Formatting changes the string representation, not the underlying 128-bit identifier. Some APIs require the hyphenated form, so check the receiving system before removing it.
A practical fixture workflow
For a test table with 20 new records, generate 20 values once, download the batch and assign one value per record. Use a database uniqueness constraint and handle an insertion conflict; generating a random identifier does not remove the need for data integrity rules.
UUID v4 contains 122 random bits. Collision risk is very small with a sound random source, but it is not zero. An identifier does not grant authorization: access control must be checked separately.
Limits and privacy
This page generates v4, not time-ordered v7 identifiers. It uses the browser’s crypto.randomUUID() on HTTPS; an unsupported browser cannot generate a batch. Generation does not send UUID values to a server.
There is no offline installer or service worker here. A page already loaded can generate IDs without a new request; a fresh offline visit or refresh is not guaranteed. Optional site analytics follows your privacy choice and is separate from UUID generation.
Sources and review scope
RFC 9562 §5.4: UUID v4 and §6.7: collision resistance. Reviewed October 11, 2026 against the standard and the controls implemented on this page. Browser tests check batch size and format; they cannot prove absence of collisions.
Boundary and failure cases
Version 4 UUIDs rely on random bits. Collision probability is extremely low for typical volumes, not zero. Databases and APIs that require uniqueness should still enforce unique constraints rather than trusting probability alone.
Hexadecimal case is a presentation choice. RFC 4122 often shows lowercase, but a case-sensitive column can store two spellings as different values. Normalize before compare. Removing dashes creates a 32-character hex string that is not a different identifier — only a different encoding.
UUIDs are identifiers, not credentials. Do not use this generator as a password, API key or session-secret source. Those need appropriately sized secrets from a credential generator and a storage design that never logs them in plaintext.