UUID Generator
Generate random UUID v4 identifiers instantly — single or bulk, with format options.
Last updated: March 25, 2026
Used 61K+ timesWhat users say
“Used this to generate 500 UUIDs for a database migration seed script. The "Copy All" feature and bulk generation saved me a lot of time.”
“Super useful for generating idempotency keys when testing payment API flows. Fast, no-signup, exactly what you need.”
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Buy me a coffeeWhat is UUID Generator?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. Formatted as 32 hexadecimal characters split into 5 groups (e.g. 550e8400-e29b-41d4-a716-446655440000), UUIDs are designed to be globally unique across all computers and all time — no central authority is needed to coordinate them. This makes them ideal for distributed databases, microservices, and any system where multiple nodes must independently create unique identifiers.
UUID v4 — which this tool generates — uses cryptographically secure random numbers for all 122 of its variable bits (6 bits are fixed for version and variant). The probability of generating the same UUID twice is so astronomically small that it is considered practically impossible: you could generate one billion UUIDs per second for 85 years and have only a 50% chance of one collision.
How to Use UUID Generator
Choose how many UUIDs to generate using the quantity dropdown (1 to 100)
Select your preferred format — lowercase (default), UPPERCASE, or without hyphens
Click "Generate" to create a fresh batch of UUIDs
Click the copy icon next to any UUID to copy it individually
Click "Copy All" to copy the entire list, one UUID per line, for bulk use
Common Use Cases
- Primary keys for PostgreSQL, MySQL, or MongoDB database records
- Unique identifiers for REST API resources (e.g. /users/{uuid})
- Request correlation IDs for distributed tracing and logging (Datadog, Jaeger)
- Idempotency keys for payment APIs (Stripe, PayPal) to prevent duplicate charges
- Session tokens and state parameters for OAuth 2.0 flows
- File and asset naming to avoid collisions in S3 or cloud storage
- Event tracking IDs for analytics pipelines
- Testing: populating fixtures and seed data with unique IDs
Example Input and Output
A UUID v4 always follows the 8-4-4-4-12 format. The version character (4) and variant bits are the only fixed portions — everything else is random.
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
(where x = random hex, 4 = version, y = variant bits 8, 9, a, or b)f47ac10b-58cc-4372-a567-0e02b2c3d479
3d5c2a9e-7f1b-4d8a-b3e6-1a2c4f8e9d0b
a1b2c3d4-e5f6-4789-8012-abcdef012345Privacy Guarantee
UUID generation uses only browser-native cryptographic APIs. No generated IDs are sent to or logged by our servers — they exist only in your browser and clipboard.
Database Indexing Tip
If using UUIDs as primary keys in PostgreSQL, consider storing them as UUID type (not VARCHAR) and using the pg_trgm extension or a BRIN index if query performance on ID columns becomes a concern.
Browser Compatibility
crypto.randomUUID() is available in all modern browsers (Chrome 92+, Firefox 95+, Safari 15.4+). This tool uses it natively — no polyfill or external library required.
Frequently Asked Questions
Are these UUIDs truly unique?
What's the difference between UUID and GUID?
What UUID version should I use?
Can I use UUIDs as database primary keys?
Are UUIDs generated here cryptographically secure?
What is the difference between UUID v4 and ULID?
How This Tool Works
The tool calls the browser's crypto.randomUUID() method, which implements RFC 4122 UUID v4 generation using the operating system's cryptographically secure random source. On older browsers, it falls back to crypto.getRandomValues() filling a 16-byte Uint8Array, then manually sets version bits (bits 12-15 to 0100) and variant bits (bits 6-7 to 10) before formatting as hex strings with hyphens.
Technical Stack