🆔 UUID Generator
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Generate UUID v4 identifiers. Uses browser crypto API — instant, secure, offline-ready.
The UUID Generator creates RFC 4122 version 4 UUIDs using the browser cryptographic random number generator (crypto.randomUUID()) rather than Math.random(), providing 122 bits of entropy per identifier with a collision probability of approximately 1 in 2.7×10¹⁸ per pair. Generate 1 to 100 UUIDs at once in uppercase or lowercase format, each following the standard 8-4-4-4-12 hexadecimal pattern with the version 4 marker at position 13. Ideal for database primary keys, API correlation IDs, and distributed system identifiers where central-sequence generation is impossible.
📋 When to Use the UUID Generator
Generate RFC 4122 version-4 UUIDs for database seeds, API test fixtures, correlation IDs, or anywhere you need identifiers that won't collide. Copy a single value or bulk-generate a list; everything is produced locally from the browser's cryptographic randomness.
⚙️ How the UUID Generator Works
The UUID Generator runs entirely in your browser using client-side JavaScript. When you interact with the tool — entering text, adjusting settings, or clicking Generate — the browser processes your input using built-in algorithms and renders the output in real time. No data is ever sent to a server. Your data stays on your device throughout the entire process.
How to Use the UUID Generator
- Set the count — Choose how many UUIDs you need (1 to 100). Default is 1.
- Choose case — Check "Uppercase" for capital letters (A-F), uncheck for lowercase (a-f).
- Click Generate — UUIDs are created instantly using your browser's cryptographic random number generator.
- Copy and use — Select and copy any UUID for use in databases, API calls, or as unique identifiers in your application.
How random are the UUIDs from the UUID Generator?
They use crypto.randomUUID(), which taps the browser's cryptographic random number generator — the same source that underpins TLS encryption. Each UUID v4 contains 122 random bits following the RFC 4122 format (xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx). You can generate up to 100 at once in uppercase or lowercase. The probability of collision is astronomically low even across billions of generated IDs.
Frequently Asked Questions
What is a UUID v4?
UUID v4 is a randomly generated 128-bit identifier, formatted as 36 characters: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. It follows RFC 4122 and is designed to be globally unique without a central authority.
Are these UUIDs truly random?
Yes. They use crypto.getRandomValues(), which provides cryptographically strong randomness. The collision probability is astronomically low — you'd need to generate billions per second for decades to have a meaningful chance of collision.
UUID vs GUID — what's the difference?
They're the same thing. GUID (Globally Unique Identifier) is Microsoft's term for UUID. Both follow the same standard and are interchangeable.
When should I use UUID instead of auto-increment?
Use UUIDs for distributed systems, when merging data from multiple sources, for public-facing IDs (prevents enumeration attacks), and when you can't rely on a central sequence generator.
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