Articles · Identity tools

UUID, ULID, ObjectId, or Nano ID?

Picking an identifier is mostly about what you want to reveal: nothing, time order, database shape, or a short URL-safe token. Start there before you generate anything.

IDs feel boring until they leak information, sort badly, or become too long for a URL. The format you choose quietly shapes debugging, indexing, copy-paste, and privacy.

Toolcore's Identity tools make it easy to try the common options without installing a package just to generate a few values.

Use UUID when boring and standard is the point

A classic random UUID is a good default when you need an opaque identifier that many databases, APIs, and logs already understand. It is not short, but it is familiar.

Use it for internal records, test fixtures, and examples where the standard 8-4-4-4-12 shape is more useful than compactness.

Use UUID v7 or ULID when order helps

If you want IDs that sort roughly by creation time, try UUID v7 or ULID. They are useful in logs, event streams, and systems where newest-first queries are common.

The tradeoff is that time-ordering says something about when a value was created. That may be fine in an admin log and less fine in a public URL.

Use ObjectId when the ecosystem already expects it

MongoDB-style ObjectId values are 24 hex characters with an embedded timestamp. Use the parser when you need to inspect a value copied from a collection, log, or migration note.

Do not use ObjectId just because it is shorter than a UUID. Use it when the surrounding database or document format already speaks that shape.

Use Nano ID when the identifier needs to be short and URL-safe

Nano ID is useful for compact strings, invite codes, demo data, and URLs where a full UUID feels too heavy. Adjust the alphabet and length to match the context.

Compact does not mean secret by default. If the value grants access, you still need enough entropy and server-side authorization.

Do not confuse identifiers with secrets

IDs identify. Secrets authorize. When you need a password, bearer token, or one-time secret, open the password or random-string tools instead of copying a UUID from a sample.

This difference matters in docs too. Calling an identifier a token can make reviewers assume it must be hidden, or worse, make people treat a real secret as harmless.

A quick decision routine

  • Need a standard opaque ID? Use UUID.
  • Need time order? Try UUID v7 or ULID, then think about what the timestamp reveals.
  • Working with MongoDB? Parse or generate ObjectId values.
  • Need a compact URL-safe string? Use Nano ID with an appropriate length.
  • Need access control? Do not stop at an ID. Use real authorization.

Common use cases

  • Use before choosing an ID format for a database row, client-side mock, URL-safe handle, or log placeholder.
  • Share with teammates who treat UUID, ULID, ObjectId, Nano ID, and passwords as interchangeable.
  • Keep near tests and seed data when you need repeatable, readable, or sortable identifiers.

Common mistakes to avoid

  • Treating IDs as secrets

    Identifiers help you refer to records. They do not automatically protect access. Use password and random-string tools for secrets.

  • Adding sortability without checking privacy

    Time-ordered identifiers can reveal creation order or approximate creation time. That is useful in logs and risky in public URLs.

FAQ

Which ID format is safest for public URLs?

Use a sufficiently random, non-meaningful value when the URL is public. Nano ID can be compact and URL-safe, but access control still belongs in your app.

When should I use ObjectId?

Use ObjectId when you are working with MongoDB-style 24-character hex values or need to inspect the timestamp embedded in one.

Are generated IDs uploaded?

No. The identity tools described here generate or parse values in your browser unless a page states otherwise.