ULID Best Practices and Mistakes Developers Make

Use ULIDs as your primary or event keys when you want time-ordered inserts, store them as fixed 26-character strings or a 128-bit binary, and never edit the characters by hand — the most common mistakes come from treating a ULID as arbitrary text rather than a structured, timestamped ID. Get the storage and handling right and you gain sortability without the index fragmentation that random UUIDs cause.

Here are the practices worth adopting and the pitfalls to avoid when working with ULIDs generated by the ByteTools ULID Generator.

Best practices

• Lean on the sort order. Since the timestamp leads, ULIDs sort chronologically as strings. Use that for cursor-based pagination and time-ordered feeds instead of adding a separate created-at sort key.
• Pick one storage form and stick to it. Store the canonical 26-character string, or the raw 128-bit binary for compactness — but keep it consistent across your schema so comparisons stay valid.
• Keep them uppercase and untouched. Crockford Base32 is case-insensitive, but normalising to one case avoids surprises in case-sensitive comparisons and indexes.
• Generate close to write time. The timestamp reflects when Generate was clicked, so create IDs near the moment you insert the record for the ordering to stay meaningful.
• Batch when seeding. Need test data? Generate up to 50 at once and Copy all rather than clicking repeatedly.

Common mistakes and how to avoid them

ULID vs UUID: choosing wisely

A random UUID (v4) is fully unordered, so using it as a clustered primary key scatters inserts across the index and hurts locality. A ULID puts the timestamp first, so new rows append near each other and reads stay cache-friendly. The trade-off is that a ULID reveals roughly when it was created — usually harmless, but a consideration for IDs you expose publicly where creation timing is sensitive.

Handling and privacy tips

Because generation runs entirely in your browser with the secure random source, you can safely produce IDs for private projects without anything being logged or transmitted. When you paste a batch into code or a seed file, keep the whole 26-character string intact — truncating it to shorten a URL destroys both uniqueness and sortability.

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

FAQ

Should I use a ULID or a UUID for a database primary key?

Prefer a ULID when insert ordering and index locality matter, since its leading timestamp keeps new rows together. Choose a random UUID when you specifically want to hide creation time.

Is it safe to sort ULIDs as plain strings?

Yes. Crockford Base32 preserves order, so sorting ULIDs as text sorts them by creation time. Just remember that IDs made in the same millisecond are ordered by their random part.

Can I shorten a ULID to save space in a URL?

No. Every character carries meaning — the timestamp and randomness together — so trimming characters breaks uniqueness and ordering. Keep all 26. Use NanoID if you need a shorter random ID.

Do ULIDs leak information?

The embedded timestamp reveals approximately when the ID was generated. That is usually fine, but if disclosing creation time is a problem for a public identifier, use a fully random ID instead.

Related free tools

• UUID Generator — for fully random, unordered IDs.
• NanoID Generator — shorter URL-safe identifiers.
• Base32 Encode — work with Base32 data directly.
• CRC-32 Generator — checksums for integrity checks.

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