UUID ↔ ULID Converter & Generator

What's the difference between UUID and ULID?

• UUID (v4): Completely random 128-bit identifier, not sortable
• ULID: Includes timestamp (timestamp + random), time-sortable

ULIDs are sorted chronologically by creation time, providing better database index performance.

How to extract timestamp from ULID?

The first 10 characters of a ULID encode the timestamp in milliseconds using Base32. This tool automatically decodes it into a human-readable date/time.

Example: 01ARZ3NDEK... → 2016-07-30T23:54:10.000Z

When to use ULID instead of UUID?

ULID is recommended when:

• You need chronological sorting by creation time
• Database index performance optimization is important
• You need to extract creation time from the ID
• Working with case-insensitive systems (ULID uses only uppercase)

What are the advantages of ULID?

• Sortable: Automatically sorted chronologically
• Shorter: 26 characters (UUID is 36)
• URL-safe: Base32 encoding, no special characters
• Case-insensitive: All uppercase
• Embedded timestamp: Creation time extractable from ID

Is UUID ↔ ULID conversion reversible?

No, the conversion in this tool is approximate. Since UUID has no timestamp information, UUID → ULID conversion uses the current time. It cannot be converted back to the original UUID.

For production use, it's recommended to generate each independently.

Is my data safe?

Yes! All generation and conversion happens only in your browser. Generated IDs are never sent to any server and are not stored anywhere.