ULID Generator

What Is ULID?

ULID (Universally Unique Lexicographically Sortable Identifier) is a unique identifier designed to retain time-ordering information. A standard ULID contains 128 bits, including a 48-bit millisecond timestamp and 80 bits of randomness, and is normally represented as a 26-character string.

Because the timestamp is stored at the beginning of the identifier, ULIDs can generally be sorted lexicographically in the same order as their creation time.

What Can the ULID Generator Do?

• Single generation: Generate one standard ULID quickly.
• Batch generation: Generate multiple ULIDs for test data and development.
• Copy results: Copy generated identifiers for use in code, databases or APIs.
• Export results: Export generated ULIDs for later use.
• ULID parsing: Analyze an existing ULID and extract its timestamp.
• Timestamp extraction: Recover the corresponding generation time from the timestamp portion.

ULID Structure

A standard ULID contains a 48-bit millisecond timestamp followed by 80 bits of random data. It is encoded using Crockford Base32 and normally displayed as 26 characters.

ULID vs UUID

Both ULID and UUID are designed for unique identification, but their design goals differ. Traditional UUIDs primarily focus on uniqueness, while ULID adds time-sortable characteristics.

• UUID: General-purpose unique identifier.
• ULID: Unique identifier containing a timestamp component.
• Length: ULID commonly uses 26 characters, while a standard UUID string commonly uses 36 characters.
• Database use: ULID can be useful when records need time-oriented ordering.

Common ULID Applications

• Database primary keys
• Distributed system identifiers
• Orders, tasks and message IDs
• API request and tracing IDs
• Logs and event identifiers
• Test data generation
• Automated API testing

How to Use the ULID Generator

1. Generate one or multiple ULIDs.
2. Copy or export the generated results.
3. Use the parsing function when you already have a ULID.
4. Inspect the timestamp and corresponding generation time.

What Does the ULID Timestamp Mean?

The first 48 bits of a standard ULID store a millisecond Unix timestamp. This allows the identifier to carry time information that can be decoded for analysis and ordering.

ULID Considerations

Although ULIDs provide a very large identifier space, they should still be selected according to the requirements of the application. Database indexing, storage type, ordering behavior and the ID generation strategy should be considered together.