ULID Generator

Runs in browser Utilities

Create Universally Unique Lexicographically Sortable Identifiers with secure randomness, optionally monotonic, and decode the embedded millisecond timestamp of any ULID.

Privacy: This tool runs entirely in your browser. Your input never leaves your device.

How to use ULID Generator

  1. Set how many ULIDs you need and click Generate.
  2. Optionally pin a timestamp for deterministic prefixes.
  3. Paste an existing ULID and click Decode to read its creation time.

ULID Generator features

  • 26-character, URL-safe, lexicographically sortable identifiers
  • Secure randomness with optional monotonic ordering within a millisecond
  • Fixed timestamp mode for reproducible test fixtures
  • Decode any ULID to its timestamp, randomness and UUID equivalent
  • Accepts UUIDs and shows their ULID form
  • Lowercase output option

ULID Generator example

Decode the canonical example ULID

Input:

01ARZ3NDEKTSV4RRFFQ69G5FAV

Output:

Timestamp: 2016-07-30T23:54:10.259Z · Randomness: TSV4RRFFQ69G5FAV · As UUID: 01563e3a-b5d3-d676-4c61-efb99302bd5b

Frequently asked questions about ULID Generator

Why choose ULID over UUID?

ULIDs are 26 characters (vs 36), URL-safe, case-insensitive and sort lexicographically by creation time, making them ideal for database keys and log correlation.

What does "monotonic" mean?

When several ULIDs are generated within the same millisecond, the random part is incremented so they still sort in creation order.

Can I decode a ULID?

Yes. Paste one and click Decode to see the embedded timestamp as ISO date, the randomness part and the equivalent UUID representation of the same 128 bits.

Why are O, I and L accepted when decoding?

Crockford Base32 excludes those letters to avoid confusion; the decoder maps O → 0 and I/L → 1 so hand-typed IDs still work.