UUID Generator is a free tool that creates universally unique identifiers: random UUID version 4, time-ordered UUID version 7, and ULIDs. Generate one or up to 1,000 at a time, in lowercase or uppercase, with or without hyphens. IDs are created in your browser with a cryptographically secure random number generator.
How to generate UUIDs
- Choose the type: v4, v7 or ULID.
- Set how many you need. A fresh set is generated immediately.
- Copy them all, download them as a text file, or click Generate new for another set.
v4, v7 or ULID?
- UUID v4 is completely random, e.g.
f47ac10b-58cc-4372-a567-0e02b2c3d479. It reveals nothing about when or where it was made. The most widely supported choice. - UUID v7 (RFC 9562) starts with a millisecond timestamp, so IDs created later sort later. As a database primary key it keeps indexes compact and inserts fast.
- ULID is also time-ordered, but written as 26 characters of Crockford Base32, e.g.
01J8Z3K5X2V7M9Q4W6T1R0N8BD, which is shorter and URL-friendly.
Shorter IDs with NanoID
Choose NanoID for short, URL-friendly IDs with the length and characters you want, for example 10 letters and numbers for a public reference. The NanoID Generator explains how to pick a safe length.
MongoDB ObjectIds
Choose MongoDB ObjectId to generate the 24-character IDs MongoDB uses for _id. The check box also reads ObjectIds and shows when they were created. For more, including turning a date into an ObjectId for queries, see the MongoDB ObjectId Generator.
Checking a UUID
Paste any UUID into Check a UUID to see whether it is valid, its version and variant, and for time-based versions (1, 6 and 7), when it was created. That helps when debugging, for example to find out when a record was inserted.
Uniqueness
UUIDs can be generated independently on any device without a central server and still be practically unique. The chance of two random v4 UUIDs ever matching is so small that it can be ignored for any real system.
Frequently asked questions
Which version should I use?
Use v4 for general-purpose random IDs. Use v7 for database keys: it starts with a timestamp, so new rows are inserted in order, which is faster for most databases. ULID has the same benefit in a shorter, URL-friendly form.
Can two generated UUIDs be the same?
Practically, no. A v4 UUID has 122 random bits; you would need to generate billions per second for many years before a collision became likely.
Is a UUID the same as a GUID?
Yes. GUID is Microsoft’s name for the same 128-bit identifier. Some Microsoft tools display them in uppercase or with braces.
Are these safe to use as secret tokens?
v4 UUIDs are generated with secure randomness, but v7 UUIDs and ULIDs reveal when they were created. For secrets such as API keys or reset links, a dedicated random token is a better choice.
Last updated