ULID resource

Health v2 · maintenance only

Adoption not part of the score

3442 stars · 116 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

The canonical specification for ULID (Universally Unique Lexicographically Sortable Identifier), a 128-bit identifier format compatible with UUID but lexicographically sortable and encoded as a 26-character Crockford base32 string. The repository also indexes community implementations of the spec in dozens of languages.

Use cases

• generate sortable unique ids for database primary keys
• replace uuid v4 with time-ordered identifiers
• implement a ulid library in a new language
• avoid index fragmentation from random ids
• url-safe case-insensitive identifiers
• monotonic ids generated within the same millisecond

When to choose

• you need the authoritative reference for the ULID format
• you are implementing or validating a ULID library
• you want a directory of existing ULID implementations across languages

When to avoid

• you need a runnable library for a specific language rather than the spec
• you need UUID compatibility with existing UUID tooling
• you require cryptographic security guarantees from identifiers

Facets

learning-resource · maturity stable

developer-tools serialization developer-tools databases cross-platform ulid identifier specification uuid-alternative sortable-ids base32 algorithms

Member repositories

For agents

markdown · JSON · MCP: product_card(name="ulid/javascript")