UUID Generator
RFC 4122 Version 4
Generate RFC 4122 UUID version 4 values in bulk for database keys, fixtures, filenames, and distributed IDs. Uses browser crypto — nothing is uploaded.
This conversion runs only in your browser — nothing is uploaded.
- Version—
- Count—
What is this tool?
This UUID generator creates RFC 4122 version 4 identifiers. A UUID v4 is a 128-bit value whose uniqueness comes from randomness (Web Crypto / crypto.randomUUID), not from a MAC address or a central counter.
The familiar string form is 36 characters with hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The version nibble is 4; the variant bits identify the RFC layout. Remaining bits are random.
Use UUIDs for database rows, file names, test fixtures, event IDs, queue messages, and distributed traces. Do not use them as passwords or bearer tokens—uniqueness and secrecy are different properties.
Common use cases
- Bulk-create primary keys or fixture IDs for local seeding and integration tests
- Mint unique file or object names without a shared sequence generator
- Produce correlation / event IDs for logs and queues in distributed systems
How to use
- Keep UUID v4 (random) selected (the only version this page supports).
- Choose how many IDs to create (1–100) and click Generate. The first UUID appears on load.
- Copy a single row, or Copy All for a newline-separated list. Clear empties the list.
- Click Generate again whenever you need a fresh batch.
Examples
| Input / setting | Output | Notes |
|---|---|---|
Count 1, Generate | One xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx | Version digit is 4; variant nibble is 8, 9, a, or b. |
Count 3, Copy All | Three lines, one UUID each | Handy for paste into CSV / SQL seed scripts. |
| Clear then Generate | Empty list → new batch | Clear does not upload; it only resets local UI state. |
| Expect time-sortable IDs | Not available here | v4 is random order—use ULID / UUID v7 elsewhere if you need insert-order sort. |
Practical pitfalls
- v4 vs other versions: v1 embeds time/node data; v5 is name-based (SHA-1); ULID and UUID v7 aim for time-sortable keys. This tool is v4 only.
- Sortable UUID need: Lexicographic or B-tree insert order of v4 values is effectively random—hot indexes and locality suffer if you assumed chronological order. Pick a sortable ID scheme when that matters.
- UUIDs are identifiers, not secrets. Anyone who sees a UUID can reuse it; do not treat it as a password or API key.
- Collision risk is negligible for honest generators, but uniqueness is probabilistic—not a mathematical proof for adversarial settings.
References
Last reviewed: 2026-07-27
Frequently asked questions
- Which UUID version does this generate?
- UUID version 4 (random) only. Version and variant bits follow RFC 4122; the rest comes from `crypto.randomUUID` / Web Crypto. v1, v5, and ULID/UUID7-style sortable IDs are not offered here.
- How many UUIDs can I create at once?
- Between 1 and 100 per batch. Use Generate again for a fresh set, or Clear to empty the list.
- Are UUIDs guaranteed unique?
- Collisions for properly generated UUID v4 values are astronomically unlikely, but not mathematically impossible. Do not treat uniqueness as a substitute for secrecy (they are not passwords).
- Are generated UUIDs uploaded?
- No. Values are created and copied in your browser only.