UUID / ULID Generator
Generate, format, validate and export IDs for apps, databases, and APIs.
What is a UUID / ULID Generator?
A UUID / ULID Generator creates unique identifiers that are commonly used as primary keys, reference IDs, request IDs, order IDs, invoice IDs, and public-facing tokens. This tool helps you generate secure, collision-resistant IDs instantly for software projects, databases, APIs, and distributed systems.
UUIDs are widely supported across platforms and frameworks, while ULIDs provide a similar uniqueness guarantee with an extra advantage: they are sortable by time, which can improve database indexing and log readability. Use this generator to produce one ID or a bulk list, then copy or download them as needed.
UUID vs ULID: Which should you use?
- UUID (v4): Random-based identifier (commonly 36 characters with hyphens). Great for general use, universally recognized, and supported by most databases and libraries.
- ULID: 26-character, Crockford Base32 identifier that is lexicographically sortable. Ideal for database rows where ordering by creation time is helpful.
Common use cases
- Database primary keys (users, orders, invoices, shipments, devices)
- Public share links where numeric IDs should not be exposed
- API request IDs and trace IDs for debugging and monitoring
- Event IDs in logs and message queues (Kafka, RabbitMQ, SQS)
- Multi-warehouse or multi-tenant systems needing unique records across locations
Best practices for storing UUIDs and ULIDs
- Keep IDs consistent: Pick one format per table or domain (UUID or ULID) to reduce confusion.
- Use fixed-length types: ULIDs fit well in
CHAR(26), UUIDs often inCHAR(36)(with hyphens). - Index wisely: ULIDs can reduce index fragmentation because they are time-sortable.
- Don’t re-generate: Treat identifiers as permanent references once issued.
- Use bulk generation: Great for test data, imports, and pre-allocating IDs for offline workflows.
Frequently Asked Questions (FAQ)
1. What is a UUID?
A UUID (Universally Unique Identifier) is a standardized identifier designed to be globally unique. It’s commonly used in databases, APIs, and distributed systems.
2. What is a ULID?
A ULID (Universally Unique Lexicographically Sortable Identifier) is a unique ID that is sortable by time. It’s compact (26 characters) and works well for database indexing and event ordering.
3. Which is better: UUID or ULID?
Both are excellent. UUIDs have universal adoption and tooling support, while ULIDs are time-sortable and often perform better in indexed database inserts. Your best choice depends on your storage and query patterns.
4. Are UUIDs and ULIDs secure?
They are not encryption, but they are hard to guess at random, especially UUID v4 and ULIDs generated with cryptographic randomness. They’re widely used as public-safe identifiers.
5. Can ULIDs be used as primary keys?
Yes. ULIDs are commonly used as primary keys and can reduce index fragmentation compared to random UUIDs because new ULIDs tend to sort after older ones.
6. Why do ULIDs sort by time?
ULIDs embed a timestamp component at the start of the identifier. That means the string naturally sorts by creation time when compared lexicographically.
7. Should I store UUIDs in binary or text?
Text storage (CHAR(36)) is easiest and most compatible. Binary storage can be more efficient,
but requires conversion functions and consistent handling across your stack.
8. Can I generate multiple IDs at once?
Yes. Bulk generation is useful for test data, CSV imports, offline-first apps, and pre-assigning IDs before insert.
9. Do UUIDs ever collide?
Collisions are extremely unlikely with properly generated UUID v4 values. In real-world applications, UUID collisions are considered practically impossible.
10. Do you store or track generated IDs?
No. This generator runs in your browser and does not store your generated UUIDs or ULIDs. You can safely use it for private projects and production workflows.
- UUID v4: random IDs (most common).
- UUID v7: time-ordered (good for DB indexes).
- UUID v5: deterministic from name+namespace.
- ULID: sortable and URL-safe.
550e8400-e29b-41d4-a716-446655440000{550e8400-e29b-41d4-a716-446655440000}urn:uuid:550e8400-e29b-41d4-a716-44665544000001J0K9Q7Q4R3V2G1A8ZB9Y6X5W (ULID)