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ULID Generator Online — Free Universally Unique Lexicographically Sortable ID

Generate ULIDs (Universally Unique Lexicographically Sortable Identifiers) in your browser with a cryptographically secure source of randomness. A ULID packs a 48-bit millisecond timestamp and 80 bits of randomness into a 26-character, Crockford Base32 string that sorts correctly by creation time — unlike a random UUID. Generate a single ULID to try it out, or produce dozens at once for seeding databases, event logs, or distributed systems that need sortable, collision-resistant IDs. Everything runs locally in the browser, so no ID ever leaves your machine.

Features

  • Lexicographically sortable

    The leading 10 characters encode the millisecond timestamp, so ULIDs sort correctly as plain strings.

  • Cryptographically secure randomness

    The 80-bit random portion comes from `crypto.getRandomValues`, the same source used for TLS keys.

  • Crockford Base32 encoding

    Uses the Crockford alphabet (no I, L, O, U) to avoid visual ambiguity and accidental profanity.

  • Bulk generation

    Generate 1 up to 50 ULIDs at once and copy them individually or all together.

How to generate a ULID online

Produce one or many ULIDs in seconds.

  1. Set the quantityEnter how many ULIDs you need — 1 for a quick paste, up to 50 for bulk seeding.
  2. GenerateClick Generate to produce the requested ULIDs. Each one is built from the current timestamp plus fresh randomness.
  3. Copy a single ULIDClick Copy next to any entry to copy just that value.
  4. Copy everythingClick Copy All to copy the full list, one ULID per line.

Examples

A single ULID

Input
count=1
Output
01ARZ3NDEKTSV4RRFFQ69G5FAV

The first 10 characters encode the millisecond timestamp; the last 16 encode 80 bits of randomness.

Frequently Asked Questions

What is a ULID?
A ULID is a 128-bit identifier encoded as a 26-character string: a 48-bit millisecond timestamp followed by 80 bits of randomness, both encoded in Crockford Base32. It is designed as a sortable, URL-safe alternative to UUID v4.
How is a ULID different from a UUID?
A standard UUID v4 is entirely random, so UUIDs generated close together in time have no relationship to each other when sorted. A ULID embeds a timestamp as its first 10 characters, so ULIDs generated later always sort after ones generated earlier — useful as a primary key or event ID.
Why does the Crockford alphabet skip I, L, O, and U?
Those letters are easily confused with the digits 1 and 0, or with each other, when read or transcribed by hand. Excluding them (and avoiding accidental spelling of words) makes ULIDs easier to communicate verbally or visually.
Can two ULIDs generated in the same millisecond collide?
It is extremely unlikely. Within the same millisecond, the 80 bits of randomness still need to collide exactly, which has the same astronomically low probability as a UUID v4 collision.
Are ULIDs safe to expose in URLs or public APIs?
Yes, in terms of format — they are case-sensitive uppercase alphanumeric strings safe for URLs and filenames. Keep in mind the timestamp portion is not secret, so avoid ULIDs if you need to hide the exact creation time of a resource.
Is this generator cryptographically secure?
Yes. The random portion of each ULID is generated with the browser's `crypto.getRandomValues`, the same cryptographically secure source used for TLS session keys.