ULID Generator

ULID stands for Universally Unique Lexicographically Sortable Identifier. It's a 26-character identifier that combines a 48-bit timestamp (millisecond precision) with 80 bits of randomness, encoded using Crockford's Base32. Unlike UUIDs, ULIDs are sortable by creation time, URL-safe, and more compact.

ULID advantages over UUID:
• Sortable: ULIDs are lexicographically sortable by time (timestamp comes first).
• Shorter: 26 characters vs UUID's 36 characters.
• URL-safe: No special characters, safe for URLs and filenames.
• Case-insensitive: Uses Base32 encoding which is case-insensitive.
• Human-readable time: You can extract the timestamp directly from a ULID.

A ULID consists of 26 characters using Crockford's Base32 alphabet: 0123456789ABCDEFGHJKMNPQRSTVWXYZ (excludes I, L, O, U to prevent confusion). The first 10 characters encode the timestamp (48-bit Unix milliseconds), and the remaining 16 characters are randomly generated (80 bits of entropy). Example: 01ARZ3NDEKTSV3TQ9Y8X6V4K2M.

Yes, for all practical purposes. The 80-bit random component provides 2⁸⁰ possible values per millisecond. This means even if you generate billions of ULIDs per second, the collision probability remains astronomically low. Combined with the timestamp, ULIDs are universally unique across distributed systems without coordination.

ULIDs are ideal for database primary keys, distributed systems, event logs, and message queues where time-based sorting matters. They work exceptionally well with databases like PostgreSQL, MySQL, and DynamoDB. Use ULIDs when you need sortable, URL-friendly unique identifiers with embedded timestamps.

Absolutely! The first 10 characters of a ULID encode the 48-bit Unix timestamp in milliseconds. Use the ULID Parser above to decode any ULID and see exactly when it was created. This is one of ULID's most powerful features — you can determine when an ID was generated without storing additional metadata.

Yes, a standard ULID is always exactly 26 characters long. The fixed length makes it predictable for database schema design, API contracts, and storage allocation. If you encounter a ULID that isn't 26 characters, it may be malformed or using a non-standard variant.