ULID Use Cases: Sortable IDs for Keys, Logs and Events

ULIDs shine wherever you want unique IDs that also sort by creation time: primary keys that insert in order, event and log identifiers, distributed record creation without a central counter, and readable seed data for tests. The leading 48-bit timestamp gives you chronological ordering for free, and 80 bits of secure randomness keep every ID unique.

Here are the scenarios developers reach for ULIDs, each with a concrete example you can generate right away.

Where ULIDs fit best

Time-ordered database keys

Imagine an orders table that receives thousands of inserts per hour. With random UUID keys, each row lands at a random spot in the index, fragmenting it. Swap in ULIDs and every new order gets an ID whose timestamp prefix places it right after the previous one, so inserts append cleanly and range scans over recent orders stay fast. Generate a handful, drop them into your seed script, and the sort order matches insertion order automatically.

Event and log identifiers

In an event stream or audit trail, you often need to both identify and order events. A ULID does both: id alone tells you which event and roughly when it happened. Sorting your log lines by ULID reconstructs the timeline without joining on a separate created-at field, which simplifies queries and keeps replay deterministic.

Distributed record creation

When several services or workers create records at once, a central auto-increment counter becomes a bottleneck and a single point of failure. Because each ULID combines the local timestamp with 80 secure random bits, any node can mint IDs independently with a vanishingly small collision risk — and the results still sort roughly by time across the whole fleet.

Seed data and fixtures

Writing tests that assert on ordering is painful with opaque random IDs. Generate 20 or 50 ULIDs at once with Copy all, paste them into your fixtures, and your test data already sorts in a predictable, timestamped order — handy for pagination tests and snapshot comparisons.

A quick workflow

1. Decide how many IDs you need and set the count (up to 50).
2. Click Generate and Copy all.
3. Paste the batch into your schema seed, fixture file or event mock.
4. Rely on the natural sort order instead of adding a separate ordering column.

Try the ULID Generator — free and 100% in your browser.

FAQ

When should I choose a ULID over a UUID?

Choose a ULID when you want IDs that sort by creation time — database keys, logs and event streams benefit most. Stick with a random UUID when you specifically need to hide when a record was created.

Do ULIDs work for distributed ID generation?

Yes. Each ULID mixes a timestamp with 80 bits of secure randomness, so independent nodes can generate them without coordination while still producing roughly time-ordered results.

Can I use ULIDs as URL identifiers?

Absolutely. A ULID is a single 26-character, dash-free, URL-safe string, so it drops straight into paths and query parameters without encoding.

How do I generate a realistic batch for tests?

Set the count up to 50, click Generate, and use Copy all to grab the whole set. Pasted into fixtures, they already carry timestamps and sort in creation order.

Related free tools

• UUID Generator — when you need fully random IDs.
• NanoID Generator — compact IDs for short URLs.
• JSON Formatter — tidy payloads that carry your IDs.
• Base32 Encode — encode data in Crockford-style Base32.

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