UUID Generator, Create Unique Identifiers Online

Uuid Generator

Generate version 4 UUIDs (universally unique identifiers) with one click. Each UUID is a 128-bit value formatted as 32 hexadecimal digits in five groups separated by hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). The generation uses crypto.getRandomValues(), the browser\'s cryptographic random source, ensuring genuine uniqueness and unpredictability. UUIDs are essential in software development for creating database primary keys, session tokens, transaction IDs, file identifiers, and API request tracking. The v4 format uses 122 random bits (6 bits are reserved for version and variant markers), producing over 5.3 x 10^36 possible values. The odds of generating two identical UUIDs are astronomically small, about 1 in a billion billion even after generating a billion UUIDs. Generate one UUID or batch up to 20 at a time. Click any UUID to copy it to your clipboard. The UUIDs are generated entirely in your browser and are never logged or transmitted.

How it works

The generator creates a v4 UUID following RFC 4122. It fills a 16-byte array with cryptographically random values using crypto.getRandomValues(). Byte 6 is masked to set the version nibble to 0100 (version 4), and byte 8 is masked to set the variant bits to 10xx (RFC 4122 variant). The bytes are then formatted as a 32-character hexadecimal string with hyphens inserted at positions 8, 12, 16, and 20, producing the standard 8-4-4-4-12 format. Multiple UUIDs are generated in a loop and rendered as individual copyable blocks.

When to use this tool

Backend developers generate UUIDs for database records to avoid sequential ID enumeration attacks. Frontend developers need UUIDs as React component keys or local state identifiers. DevOps engineers create unique deployment or build identifiers. QA testers generate test data with realistic unique IDs. API developers use UUIDs as idempotency keys to prevent duplicate request processing. Designers use UUIDs as placeholder content in mockups that will eventually contain real IDs.

Frequently asked questions

What is a UUID and when should I use one?

A UUID (Universally Unique Identifier) is a 128-bit number used to identify information uniquely without central coordination. Use UUIDs when you need IDs that are unique across distributed systems, for example, database records created on different servers that must never have colliding keys.

Are these UUIDs safe for production use?

Yes. They are generated using crypto.getRandomValues(), which provides cryptographic-grade randomness suitable for security-sensitive applications. The output conforms to RFC 4122 version 4 format.

What are the odds of generating a duplicate UUID?

Vanishingly small. With 122 random bits, you would need to generate about 2.7 x 10^18 (2.7 quintillion) UUIDs before having a 50% probability of a single collision. In practical terms, generating one billion UUIDs per second for 86 years would give you a 50% chance of one duplicate.

What is the difference between UUID v1 and v4?

UUID v1 incorporates a timestamp and MAC address, making it partially predictable and potentially leaking device information. UUID v4 is purely random, offering better privacy and unpredictability. This tool generates v4 exclusively.

Can I generate UUIDs in bulk?

Yes. Use the counter to generate up to 20 UUIDs at once. Each is displayed in a separate copyable block. For larger batches (hundreds or thousands), a script-based approach would be more practical.

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