What is ULID Generator?

When you need unique IDs that are shorter and more readable than UUIDs, or want identifiers that can be sorted chronologically—this tool can help. ULID (Universally Unique Lexicographically Sortable Identifier) generates a 26-character unique identifier combining timestamp and randomness.

• 128-bit format compatible with UUID
• Lexicographically sortable (timestamp-based)
• 26 characters and URL-safe (shorter than UUID's 36 characters)
• Supports three generation methods: default, time seed, and monotonic

Useful as a UUID alternative for database primary keys, log tracking, distributed system identifiers, and many other scenarios.

How to Use

Select a generation method, enter seed time if needed, then click the "Generate ULID" button. Generated ULIDs will appear in the result area.

You can specify the quantity to create multiple ULIDs at once (1-100).

ULID Features

Differences from UUID

• Shorter: 26 characters (UUID is 36 characters)
• Sortable: Timestamp-based, can be arranged chronologically
• URL-safe: No special characters
• Readable: Base32 encoding for better readability
• Case-insensitive: More resistant to input errors

Structure

ULID consists of a 48-bit timestamp (milliseconds) and 80 random bits.

01ARZ3NDEKTSV4RRFFQ69G5FAV
|------------|------------|
  Timestamp      Random
  (10 chars)    (16 chars)

Generation Methods

Default

Combines timestamp and random bits. The most common usage.

Time Seed

Generates using the specified seed time. With the same seed time, the timestamp portion (first 10 characters) will be identical, but the random portion differs, producing different ULIDs.

Monotonic

Generates ULIDs by incrementing the least significant bit by 1 within the same millisecond. Use when strict ordering is required.

Benefits of ULID

Chronologically Sortable

Timestamp-based, so they can be sorted by generation order. Ideal for chronological management of logs and events.

Database-Friendly

Sequential nature makes database indexing more efficient than UUIDv4.

Short and Readable

At 26 characters and URL-safe, they're easy to use in URLs and filenames, with a human-readable format.

For more details, see the ULID specification.