ULID Generator
Generate Universally Unique Lexicographically Sortable Identifiers for databases, APIs, and distributed systems. The backend returns a single Crockford Base32 ULID with no configuration required.
Generates a single 128-bit ULID per request.
Encodes as 26 Crockford Base32 characters (no special characters).
Lexicographically sortable by millisecond timestamp for roughly chronological ordering.
Useful for database primary keys, API IDs, event logs, and fixtures.
No configuration — click Generate and copy.
How to Use
Open the ULID Generator page
Click Generate to create a new ULID (one is created on page load)
Copy the value with the copy button
Use it in records, APIs, tests, or migrations
Backend Development
- Create sortable database identifiers
- Generate API request IDs
- Seed test fixtures
Distributed Systems
- Create globally unique event IDs
- Avoid centralized integer ID allocation
- Keep logs roughly ordered by millisecond timestamp
Developer Workflows
- Databases
- REST APIs
- Event logs
- Test fixtures
ULIDs sort lexicographically by their embedded millisecond timestamp, which generally helps B-tree index locality.
Crockford Base32 avoids ambiguous characters (I, L, O, U) for safer human transcription.
Prefer ULID or UUID v7 when you need uniqueness plus rough chronological ordering.
Use ULIDs when you want unique IDs that roughly sort by creation time.
Do not treat ULID secrecy as an authorization mechanism.
Store and compare ULIDs as opaque strings unless you intentionally decode the timestamp.
Frequently Asked Questions
Find answers to common questions about our tools and services.
Understanding ULID Generator
A ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier designed as a practical alternative to UUID for systems that need uniqueness and roughly chronological sortability. The high 48 bits encode a Unix timestamp in milliseconds; the remaining 80 bits are cryptographically random. The binary value is encoded with Crockford Base32 into a fixed 26-character string that is URL-safe and case-insensitive for decoding.
Compared with random UUID v4, ULIDs insert near the end of B-tree indexes when used as primary keys, reducing page splits and improving write locality. Compared with UUID v7, ULIDs offer a compact non-hyphenated string form that many APIs and log formats prefer, while still providing timestamp-sortable uniqueness.
This ULID Generator calls the existing backend processor, which uses a cryptographically secure random source and the current timestamp. Each Generate click returns one new ULID ready to copy into fixtures, migrations, or application code.