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Need a special ID? A UUID generator is one of those tools that developers use all the time, whether they're making test data, setting up database records, or making API keys. You can choose from UUID v4, ULID, and NanoID formats with this one.

UUID v4: The Classic Choice UUID v4 is the format that most people use. It is a random 128-bit number that looks like this: 550e8400-e29b-41d4-a716-446655440000.

The chances of making a copy are so small that they are almost impossible.

There are 2^122 possible combinations. You could make a billion UUIDs every second for 85 years and still have less than a 50% chance of a collision. I use UUID v4 for a lot of things, like session tokens, database primary keys, file identifiers, and tracking IDs.

If you don't have any special needs and just need something unique, this is the default option. ULID: When Sorting Matters ULIDs (Universally Unique Lexicographically Sortable Identifiers) fix a real problem with UUIDs: they can be sorted by when they were made.

The first 48 bits of a ULID encode a timestamp and look like 01ARZ3NDEKTSV4RRFFQ69G5FAV.

This is important if you want to use IDs as primary keys in a database and want them to be roughly sorted by when they were created. When you use regular UUIDs, new records get spread out randomly throughout your index. ULIDs are naturally sequential, which is better for how well a database works.

NanoID: Short and Sweet NanoID makes shorter IDs by default, usually 21 characters long, compared to UUID's 36 characters. They are similar to V1StGXR8_Z5jd.Hi6B-myT.

Same level of uniqueness guarantees, but a smaller footprint.

When the identifier shows up in URLs or places where users can see it, I use NanoID instead of a full UUID. By default, it's safe for URLs and uses a bigger alphabet, so you get the same amount of randomness in fewer characters. Bulk Generation Do you need more than one?

You can make up to 1000 identifiers at once with the UUID generator. Choose your format, enter the number you want, and click "generate." You can copy the results one at a time, which is great for pasting into a script or SQL insert statement.

I really do use the bulk feature all the time when I'm making test data.

A lot faster than writing a script to make them.

What kind of format should you use

Here's what I think quickly: UUID v4 is the best choice for most database and backend use cases.

ULID is the best choice when you need IDs that can be sorted by time, especially as primary keys. Use NanoID when you need shorter IDs for URLs or things that users see. All three of them make it almost impossible for things to collide.

Give it a try for free.