UUID and ULID Generator

Choose a format, enter a whole number from 1 to 100, then select Generate IDs. Each ID appears on its own line. Copy all IDs copies the current batch. Changing the format or count prepares the next batch and keeps the current results until you generate again. Clear results removes the batch without clearing the separate validation input.

Generation uses your browser's cryptographic random-number API. UUID v7 and ULID also use your device clock. If generation fails, the previous batch is kept; check the error message before using it as a new batch.

UUIDs are 128-bit identifiers written as 36 characters, including four hyphens. UUID v4 uses 122 random bits after the version and variant fields. This tool's UUID v7 uses a 48-bit Unix timestamp in milliseconds and 74 random bits after those fields. RFC 9562 also allows UUID v7 implementations to use optional submillisecond values or counters in that remaining space.

ULID combines a 48-bit millisecond timestamp with 80 random bits, encoded as 26 Crockford Base32 characters. Its alphabet excludes I, L, O and U. Generated ULIDs are uppercase; this validator also accepts lowercase input.

UUID v7 and ULID can be useful for time-oriented database identifiers. Their timestamps can reveal an approximate generation time. An embedded timestamp is not proof of when a record was created: the originating clock may be incorrect, and a value can be constructed manually.

Open Validate an ID, paste one value and select Validate or press Enter. The input limit is 128 UTF-16 code units, including surrounding whitespace; surrounding whitespace is ignored after the length check. Validation supports hyphenated UUIDs with version fields 1–8 and variant bits 10, plus the special all-zero Nil and all-one Max UUIDs. It also checks the ULID alphabet, length and 128-bit upper bound.

For a fixed UUID v7 example, try 017f22e2-79b0-7cc3-98c4-dc0c0c07398f. Its embedded timestamp is 2022-02-22T19:22:22.000Z in UTC. This is the published RFC example, not a newly generated unique value. A fixed UUID v4 example is 550e8400-e29b-41d4-a716-446655440000; v4 has no embedded timestamp.

The tool displays timestamps only for supported UUID v7 and ULID values. A valid result confirms the supported format, not existence in a database, uniqueness, authenticity or the correctness of version-specific fields in every UUID version.

This generator draws independent random values for each UUID v7 and ULID. It does not implement a monotonic counter. IDs generated in the same millisecond are not guaranteed to sort in generation order, and a clock moving backward can also reverse timestamp order. Database representation and collation affect sorting.

Random IDs can collide. With ideal independent uniform randomness, about 2.71 quintillion UUID v4 values give roughly a 50% chance of at least one collision. That estimate is not a guarantee for any browser, application or random-number source. Use a database uniqueness constraint and handle collisions where required.

Do not treat these identifiers as secret authentication tokens. Choose a purpose-built cryptographic token mechanism for password resets, sessions and similar security-sensitive uses.

If automatic copying fails, select the results and copy them manually. If a write remains pending, another automatic copy cannot start until it settles. After about five seconds without confirmation, the tool reports that copying is unconfirmed. Background tabs or a sleeping device can delay the notice. An earlier native clipboard write cannot be canceled and may still complete late; check the content where you paste it.

Input and generated IDs are processed in your browser without being sent to the tool's processing server. Site-wide advertising and usage measurement make separate network requests.

For database design and version-selection tradeoffs, read our practical guide to UUID v1, v4 and v7. Match the format to your system's requirements rather than relying on an identifier as proof of event order.

See RFC 9562: Universally Unique IDentifiers for UUID layouts and examples, and the ULID specification for encoding and optional monotonic generation.