ULID Generator — Complete Guide

ULIDs solve a real frustration with random IDs: they are unique like a UUID but also sort by creation time, which makes them far friendlier as database keys. A ULID generator produces these 26-character identifiers on demand for seed data, testing, and prototyping.

What is the ULID Generator?

A ULID (Universally Unique Lexicographically Sortable Identifier) is a 26-character string combining a 48-bit timestamp with 80 bits of randomness, encoded in Crockford base32. The ULID Generator produces valid ULIDs you can use wherever you need a unique, time-ordered identifier. The leading timestamp means ULIDs generated later sort after earlier ones as plain text, so they cluster naturally in databases and indexes — a property random UUIDs lack — while the random tail keeps them effectively collision-free. It is completely free, runs entirely in your browser, and needs no signup. Nothing you enter is uploaded to a server, there are no usage limits, and you can generate again as many times as you like until a result fits.

How to Use

Generating a ULID takes only a moment:

• Choose how many ULIDs you need if the tool offers a batch option.
• Click Generate to produce one or more ULIDs.
• Copy them into your seed data, fixtures, or prototype.
• Note how ULIDs generated in sequence sort in order.
• Generate again for a fresh set whenever you need them.

You can open the ULID Generator and start generating right away. Because it runs instantly and for free, it costs nothing to generate several times and keep the result that works best.

Use Cases

ULIDs suit identifier-driven work:

• Sortable primary keys in seed and test data
• Prototyping records that benefit from time ordering
• Correlation IDs that you want to sort chronologically
• Mock API payloads referencing resources by ID
• Learning how time-ordered identifiers behave
• Any place a UUID would work but ordering helps

Across all of these, the appeal of the ULID Generator is the same: a fast, unbiased, repeatable result that would take far longer to assemble by hand, available the moment you need it.

Tips

Get the most from ULIDs:

• Use ULIDs when you want unique IDs that also sort by creation time.
• For production, generate ULIDs in your application code rather than pasting from a tool.
• Remember the first ten characters encode the timestamp and the rest are random.
• If you only need uniqueness and not ordering, a UUID v4 is equally valid.

FAQ

What is a ULID?

A ULID is a 26-character unique identifier that combines a millisecond timestamp with random bits, encoded in a sortable base32 alphabet. It is unique like a UUID but, crucially, sorts in the order it was created.

How is a ULID different from a UUID?

Both are unique identifiers, but a UUID v4 is fully random and unsortable, whereas a ULID embeds a timestamp so the IDs sort chronologically as text. ULIDs are also slightly shorter and use a more compact encoding.

Why does sortability matter?

Time-ordered identifiers cluster recent records together in database indexes, which improves insert and range-query performance. Random UUIDs scatter across the index, which can fragment it; ULIDs avoid that while keeping uniqueness.

Are ULIDs guaranteed unique?

With 80 bits of randomness per millisecond, collisions are astronomically unlikely in practice, so generated ULIDs can be treated as unique for any realistic workload — the same guarantee that makes UUIDs safe to use.

Should I generate ULIDs for production in a browser tool?

Use this generator for seed data, fixtures, and prototyping. In production, generate ULIDs in your application code with a maintained library so the timestamp reflects the real creation moment and the IDs are minted where they are used.

Related Generators

If the ULID Generator is useful, you will likely reach for Bulk UUID v4 Generator, API Key Generator, and Serial Number Generator. They pair naturally with it when you need unique, well-structured identifiers for records, and exploring a few of them together often turns one quick task into a finished piece of work.

Try the ULID Generator for free at Generator Collection — open the ULID Generator and generate as much as you need. There is nothing to install and no account to create, so you can return and generate more whenever the next project comes along.