Developer utilities
UUID Generator (v4)
Generate cryptographically random version 4 UUIDs, one or in batches.
Version 4 UUIDs use 122 random bits from the browser's cryptographic generator. Up to 100 at a time. Nothing is sent to the server or stored.
Generated UUIDs appear here. Choose a count, then select Generate.
How to use the UUID generator
- Choose how many UUIDs you need, up to 100 per batch.
- Select Generate, or press Enter in the count field.
- Copy a single identifier, or use Copy all for the whole list.
- Select Generate again for a fresh set; every batch is newly randomised.
UUIDs are produced with the browser's cryptographic random generator and never leave your device. Nothing is sent to FKINFAST servers or stored.
What UUID v4 actually is
A version 4 UUID is a 128-bit identifier where 122 bits are random and the remaining bits mark the version and variant. It is written as 32 hexadecimal digits in five hyphenated groups, such as f47ac10b-58cc-4372-a567-0e02b2c3d479.
- This generator follows RFC 4122: the version nibble is
4and the variant bits are8,9,aorb. - Randomness comes from
crypto.getRandomValues, the same source used for cryptographic keys, notMath.random. - With 122 random bits, generating billions of UUIDs still leaves collision odds negligible for practical purposes.
UUID v4 compared with other versions
| Version | Basis | Notes |
|---|---|---|
| v1 | Timestamp + node/MAC address | Sortable-ish but leaks the machine identity and time. Avoid for public identifiers. |
| v4 | 122 random bits | What this tool generates. Unpredictable and unlinkable; not sortable by creation time. |
| v5 | SHA-1 of a namespace and name | Deterministic: the same input always produces the same UUID. Good for stable keys. |
| v7 | Unix time + random bits | Time-ordered and index-friendly. Use it when database insert locality matters. |
This page intentionally generates only v4. Deterministic v5 and time-ordered v7 have different inputs and trade-offs and are not interchangeable.
Common UUID mistakes
- Rolling your own with Math.random
- Math.random is not cryptographically secure and can collide or be predicted. Use crypto.getRandomValues or crypto.randomUUID, as this tool does.
- Sorting a table by a v4 primary key
- v4 values are random, so inserts land all over the index. Use a v7 or ULID when insertion order matters.
- Truncating a UUID to save space
- Chopping characters destroys the version and variant bits and sharply raises collision risk. Store the full 128-bit value or hash it properly.
- Treating a UUID as authorization
- Random UUIDs are hard to guess, but they are identifiers, not credentials. Check ownership on every request.
UUID FAQ
Can I use these UUIDs in production?
Yes. They are standard RFC 4122 version 4 identifiers generated from the browser's cryptographic random source, which is suitable for database keys, request IDs and correlation IDs.
Are the UUIDs tracked or stored?
No. Generation happens entirely in your browser with no network request, and the values exist only in the page until you copy them.
Why does the same batch not repeat when I switch tabs and return?
The list is kept in page memory, not storage. Reloading or clearing resets it, and each Generate creates new random values rather than reusing old ones.
Should I store UUIDs as text or binary?
Both are fine. Text (36 characters with hyphens, or 32 without) is simpler to debug. Binary uuid or uniqueidentifier columns save space and sort consistently; PostgreSQL also has a dedicated uuid type.