UUID v4 Generator

Generate cryptographically secure UUID v4 identifiers for databases, APIs, and applications. Generate single or multiple UUIDs. All processing is local.

How it works

What is a UUID?

UUID (Universally Unique Identifier) is a 128-bit identifier that is guaranteed to be unique across space and time. UUID v4 uses random numbers to generate identifiers, making them ideal for distributed systems where coordination is difficult.

How to Use the UUID Generator

Click "Generate UUID" to create a single UUID v4 identifier. To generate multiple UUIDs, enter a count between 1 and 100 in the count field and click generate. All UUIDs will be displayed, one per line, ready to copy.

Example 1: Single UUID

Generated UUID: 550e8400-e29b-41d4-a716-446655440000

This is a standard UUID v4 format: 8-4-4-4-12 hexadecimal characters separated by hyphens.

Example 2: Multiple UUIDs

Generate 5 UUIDs:

550e8400-e29b-41d4-a716-446655440000\n6ba7b810-9dad-11d1-80b4-00c04fd430c8\n6ba7b811-9dad-11d1-80b4-00c04fd430c8\n6ba7b812-9dad-11d1-80b4-00c04fd430c8\n6ba7b813-9dad-11d1-80b4-00c04fd430c8

UUID v4 Format

UUID v4 follows this format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

Where:

  • x is any hexadecimal digit (0-9, a-f)
  • 4 indicates version 4 (random UUID)
  • y is one of: 8, 9, a, or b

Common Use Cases

UUIDs are widely used in software development:

  • Database Primary Keys: Unique identifiers for database records
  • API Tokens: Secure tokens for API authentication
  • Session IDs: Unique session identifiers
  • File Names: Unique file identifiers
  • Distributed Systems: Unique IDs across multiple servers
  • Event IDs: Unique identifiers for events and logs

UUID v4 vs Other Versions

RFC 4122 defines several UUID versions. UUID v4 (random) is the most common for general-purpose identifiers:

  • UUID v4: Random 122 bits. Best for distributed systems, APIs, and when you need unpredictable IDs. No coordination required.
  • UUID v1: Time-based with MAC address. Predictable ordering but may leak hardware info. Use when temporal ordering matters.
  • UUID v5: Name-based (SHA-1 hash of namespace + name). Deterministic: same input always yields same UUID. Use for reproducible IDs from names.

This tool generates UUID v4 because it is the standard choice for database keys, session IDs, and API tokens.

Frequently Asked Questions

Are these UUIDs cryptographically secure?

Yes. UUIDs are generated using crypto.randomUUID() or crypto.getRandomValues(), which provide cryptographically secure random numbers suitable for security-sensitive applications.

Can I generate more than one UUID at once?

Yes. You can generate between 1 and 100 UUIDs in a single run. Each UUID is displayed with an individual copy button, and you can copy all UUIDs at once with the "Copy All" button.

What is the difference between UUID v4 and v1?

UUID v4 uses random numbers and has no predictable structure. UUID v1 is based on timestamp and MAC address, so it has temporal ordering but can reveal hardware information. For most use cases, v4 is preferred.

Are UUIDs guaranteed to be unique?

UUIDs are designed to be practically unique. The probability of a collision is astronomically low (about 1 in 2^122 for v4). For typical applications, you can treat them as unique.

Can I use these in production?

Yes. The generator uses standard Web Crypto APIs. UUIDs are suitable for production use in databases, APIs, and distributed systems.

Privacy & Security

UUID generation happens entirely in your browser using cryptographically secure random number generation. No data is sent to any server, ensuring complete privacy.

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