UUID / ULID Generator

How it works

Every identifier is built from the browser's cryptographic random source, so nothing is predictable and nothing is sent to a server. UUID v4 fills 122 bits with randomness. UUID v7, standardised in RFC 9562, starts with a 48-bit Unix millisecond timestamp, then a version nibble of 7, the variant bits 10, and 74 random bits, so values sort by creation time while staying unique. A ULID packs the same 48-bit timestamp and 80 random bits into 26 Crockford base32 characters, which avoids the easily confused letters I, L, O and U. For v7 and ULID the status line decodes the embedded timestamp of the first result so you can confirm it.

Which kind should I use?

• UUID v4 when you only need a unique, unguessable identifier and order does not matter: session tokens, idempotency keys, file names.
• UUID v7 for database primary keys. Because new values are larger than old ones, B-tree indexes stay compact and rows created together sit together on disk. Most modern databases accept it in a standard uuid column.
• ULID when you want the same time ordering in a shorter, URL-safe string with no hyphens, for example in logs, object storage keys or public URLs.
• Removing hyphens produces the 32-character hex form some APIs and column types expect; upper case is purely cosmetic because UUIDs are case-insensitive.

Privacy

Generation happens entirely on your device. The site never sees the identifiers you create.