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UUID Generator
v1, v4, ULID.
Settings
v4 random · v1 time · ULID base32.
1 to 1000. Batches to seed databases.
Result (0)
How this tool works
A UUID (Universally Unique Identifier) is a 128-bit identifier designed to be unique across billions of systems without central coordination. Version 4 (v4) uses random bits and is the go-to choice for database primary keys, session IDs or file names.
ULID is a modern alternative: 26 chars in Base32, lexicographically sortable by time, no hyphens. Ideal when you need unique IDs that also sort chronologically in logs or indexes.
How to use it, step by step
- 1
Pick a version
v4 = random (default). v1 = time + MAC. ULID = time-sortable, base32.
- 2
Set a count
1 for one-off use, up to 1000 for seeding a DB or test table.
- 3
Copy or export
Copy button for single value. Download .txt for batches.
Use cases
- Primary keys in PostgreSQL, MySQL, Mongo
- Session, tracking and feature-flag IDs
- File names uploaded to S3 / R2 / Cloudflare
- Correlation IDs in distributed logs
- Idempotency keys for Stripe, webhooks, job queues
Frequently asked questions
- Can UUID v4 collide?
- Mathematically yes, but probability is ~1 in 10³⁶. You'd need 2.7×10¹⁸ UUIDs before collision becomes plausible.
- v4 or ULID?
- v4 if you only care about uniqueness. ULID if you need insertion order recoverable from the ID or better index cardinality.
- Does v1 leak my MAC address?
- In some implementations, yes. Prefer v4 unless you need the timestamp component.
- How do I store a UUID in a database?
- Use the native type: UUID in PostgreSQL, BINARY(16) in MySQL for performance, ObjectId / String in Mongo.