What is UUID Generator?
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 36 characters (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are used as primary keys in databases, correlation IDs in microservices, session tokens, file names, and anywhere you need a globally unique value without a central authority. UUID version 4 (random) is the most common variant — it generates identifiers using cryptographically secure random numbers. The probability of generating a duplicate UUID v4 is approximately 1 in 5.3 × 10^36, making collisions practically impossible for any real-world application. Our free UUID Generator creates RFC 4122-compliant UUID v4 strings instantly using your browser's Web Crypto API. Generate one UUID or bulk-generate multiple IDs at once. Perfect for developers seeding databases, testing APIs, creating mock data, or assigning unique identifiers in distributed systems — all without installing any software.
How to Use UUID Generator
- Open the UUID Generator on ToolMaster
- Click "Generate UUID" to create a new random UUID v4
- Click "Copy" to copy the UUID to your clipboard
- Generate multiple UUIDs if you need bulk IDs for database seeding
- Paste the UUID into your code, database, API request, or configuration file
- Regenerate anytime — each click produces a completely unique identifier
Examples
Database Primary Key
Assign a unique ID to a new user record in PostgreSQL or MongoDB.
Input
Click Generate
Output
f47ac10b-58cc-4372-a567-0e02b2c3d479
API Correlation ID
Track a request across microservices with a unique trace ID.
Input
Generate UUID for HTTP header X-Correlation-ID
Output
6ba7b810-9dad-11d1-80b4-00c04fd430c8
Mock Data Generation
Create test fixtures with unique identifiers for unit tests.
Input
Generate 5 UUIDs for test user records
Output
5 unique RFC 4122-compliant UUID v4 strings
Key Features
- RFC 4122 Compliant — Standard UUID v4 format with correct version bits
- Crypto-Secure Random — Uses Web Crypto API for true randomness
- One-Click Copy — Copy UUID to clipboard instantly
- Bulk Generation — Generate multiple UUIDs at once
Why is UUID Generator Safe?
UUIDs are generated locally using crypto.getRandomValues() in your browser. No identifiers are logged, stored, or transmitted to any server.
Who Should Use UUID Generator?
Essential for developers and engineers building systems that need unique identifiers.
- Backend DevelopersGenerate primary keys and correlation IDs for APIs
- Database EngineersSeed databases and create test data with unique IDs
- DevOps EngineersAssign unique identifiers in infrastructure automation
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Frequently Asked Questions
What is a UUID v4?
UUID v4 is a randomly generated 128-bit identifier defined by RFC 4122. It contains 122 random bits and 6 fixed bits indicating version and variant. Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx.
Are generated UUIDs truly unique?
UUID v4 has 2^122 possible values. The chance of collision is astronomically low — you would need to generate billions of UUIDs per second for centuries to have a meaningful collision risk.
UUID vs GUID — what is the difference?
They are the same thing. GUID (Globally Unique Identifier) is Microsoft's term for UUID. Both refer to the same 128-bit identifier standard.
Can I use these UUIDs in production databases?
Yes. UUIDs generated with crypto-secure randomness are suitable for production primary keys, session IDs, and distributed system identifiers.
How do I generate a UUID in JavaScript?
Use crypto.randomUUID() in modern browsers, or use our tool for instant generation without writing code.
Is this UUID generator free?
Completely free with unlimited generation. No account required.
Is the UUID Generator really free?
Yes, completely free with no usage limits. You can use the UUID Generator as many times as you need without creating an account or paying anything.
Are my files uploaded to a server?
No. All processing happens locally in your browser. Your generation requests never leave your device, ensuring complete privacy and security.
What file formats are supported?
The UUID Generator supports common formats relevant to database primary keys and distributed system IDs. Check the tool interface above for specific format options and size limits.
Can I use this tool on mobile?
Yes! The UUID Generator is fully responsive and works on smartphones, tablets, and desktop computers with any modern browser.