Free UUID Generator
Create random UUIDs (v4) instantly. This tool generates universally unique identifiers for your software projects, databases, or any application requiring a unique key. Simply choose how many you need and copy them with one click.
UUID Generator
Generate random UUID v4 identifiers instantly.
About UUID v4
UUID v4 is a randomly generated 128-bit identifier represented as 32 hexadecimal digits displayed in 5 groups separated by hyphens. The probability of generating duplicate UUIDs is extremely low, making them suitable for unique identifiers in distributed systems.
How the UUID Generator Works
This tool generates UUID version 4 (random) identifiers using your browser's built-in cryptographic random number generator. No data leaves your device.
The generator uses the Web Crypto API's crypto.randomUUID() when available. For older browsers, it falls back to generating 16 random bytes and manually setting the version 4 and RFC 4122 variant bits.
Generated UUID format:
xxxxxxxx-xxxx-4xxx-Nxxx-xxxxxxxxxxxxThe "4" indicates version 4 (random). N must be 8, 9, A, or B for RFC 4122 compliance.
Real Use Cases
Database record IDs
A backend developer needs unique primary keys for a distributed database where auto-increment won't work across multiple nodes.
Session tokens
Generating anonymous session identifiers for users who haven't logged in yet, avoiding any PII in the token itself.
File upload tracking
A frontend app assigns each file upload a UUID before sending, letting users track progress without exposing server internals.
Test data generation
QA engineers need realistic unique identifiers when populating staging environments with mock user accounts or orders.
API request correlation
Adding a UUID to each incoming request so logs across multiple microservices can be traced back to a single user action.
Offline-first app sync
Mobile apps generate UUIDs locally for new records, avoiding conflicts when syncing back to the central database later.
What to Know Before Using
Browser support: Requires a modern browser with Web Crypto API support (Chrome 37+, Firefox 34+, Safari 11+, Edge 79+). Older browsers will still work but use a JavaScript fallback.
Collision probability: With UUID v4, you'd need to generate about 2.71 quintillion UUIDs to have a 1 in a billion chance of a single collision. For practical purposes, they're unique.
Not cryptographically secure for secrets: While UUIDs use random bytes, they're not meant to be used as API keys or passwords. The structure is predictable (version and variant bits are fixed).
Batch generation: You can generate up to 1000 UUIDs at once. Each is independent and equally random.
FAQ
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information. It's typically displayed as 32 hexadecimal digits in 5 groups separated by hyphens, like 550e8400-e29b-41d4-a716-446655440000.
What's the difference between UUID and GUID?
They're the same thing. GUID (Globally Unique Identifier) is Microsoft's term for UUID. The only practical difference is formatting: GUIDs are often uppercase with curly braces like {550E8400-E29B-41D4-A716-446655440000}, while UUIDs are lowercase without braces.
What does UUID version 4 mean?
Version 4 means the UUID is generated from random numbers. Other versions exist: v1 uses timestamp and MAC address, v3 and v5 are name-based (using MD5 or SHA-1 hashes), and v2 is DCE Security. Version 4 is the most common for general use.
Can I use UUIDs as primary keys in my database?
Yes, UUIDs work well as primary keys, especially in distributed systems. They're 128 bits (16 bytes), so larger than typical integer keys. Consider using CHAR(36) or BINARY(16) storage. PostgreSQL has a native UUID type.
Are UUIDs URL-safe?
Standard UUIDs contain hyphens, which are valid in URLs but sometimes need encoding. If you need URL-safe identifiers, consider removing hyphens (32 characters) or using base64url encoding. The hyphen-free format is still a valid UUID representation.
How do I validate a UUID?
A valid RFC 4122 UUID matches this pattern: 8-4-4-4-12 hexadecimal digits. The version digit (13th character) should be 1-5, and the variant digit (17th character) should be 8, 9, A, or B for standard UUIDs. Use our UUID Validator tool to check specific values.
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