UUID Generator
UUIDs are the standard way to assign unique identifiers to database records, API resources, distributed system events, and countless other objects that need a label guaranteed to be unique without coordination between servers. This free UUID generator creates version 4 UUIDs using your browser's built-in cryptographic random number generator, so each identifier is truly random and safe for production use. If you need a secure credential instead of an identifier, use the Password Generator. Generate a single UUID for a quick test or batch up to fifty at once when you need to seed a database, populate fixtures, or prepare test data. To verify data integrity when transferring UUIDs, compute a checksum with the Hash Generator. Toggle between lowercase and uppercase to match the convention your codebase follows. Every UUID is displayed in its own row with a dedicated copy button, and a bulk copy option grabs all of them at once. No data leaves your browser — everything happens locally on your device.
UUID v4 Format
A UUID v4 is a 128-bit identifier displayed as 32 hexadecimal digits in five groups separated by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The 4 in the third group indicates the version. The first digit of the fourth group is always 8, 9, a, or b, indicating the variant. All other digits are randomly generated, giving roughly 2122 possible values.
How to Use This Tool
- Set the number of UUIDs you want to generate (between 1 and 50) using the count input.
- Optionally check the Uppercase box if you need UUIDs with uppercase hex characters (A-F instead of a-f).
- Click Generate to create your UUIDs. Each one appears in a list with its own copy button.
- Use the individual Copy buttons or the Copy All button to grab UUIDs and paste them into your code, database, or configuration files.
Examples
Single UUID (lowercase)
f47ac10b-58cc-4372-a567-0e02b2c3d479
Single UUID (uppercase)
F47AC10B-58CC-4372-A567-0E02B2C3D479
Batch of 5 UUIDs for database seeding
550e8400-e29b-41d4-a716-446655440000 6ba7b810-9dad-11d1-80b4-00c04fd430c8 7c9e6679-7425-40de-944b-e07fc1f90ae7 a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11 b3d4e872-5c6a-4f39-8e1a-2b7d8f9c0e12
What This Tool Is Useful For
- Database primary keys: Use UUIDs as primary keys in PostgreSQL, MySQL, MongoDB, or any database to avoid sequential ID guessing and enable distributed inserts without conflicts.
- API resource identifiers: Assign UUIDs to REST or GraphQL resources so clients can reference objects with globally unique, non-guessable IDs.
- Test data and fixtures: Generate batches of UUIDs to populate seed files, mock data, or integration test fixtures without manual typing.
- Distributed tracing: Use UUIDs as correlation or trace IDs to link log entries across microservices and message queues.
- File and asset naming: Rename uploaded files or generated assets with UUIDs to prevent naming collisions in cloud storage buckets.
Frequently Asked Questions
- What is a UUID?
- A UUID (Universally Unique Identifier) is a 128-bit value used to identify resources without requiring a central registration authority. Version 4 UUIDs are generated using random or pseudo-random numbers, making collisions statistically negligible — the chance of generating the same UUID twice is roughly 1 in 2^122.
- Are UUIDs generated here truly random?
- Yes. This tool uses the Web Crypto API (crypto.randomUUID()), which provides a cryptographically secure random number generator built into your browser. The randomness quality is suitable for production use including database primary keys, session tokens, and correlation IDs.
- Does it matter if I use uppercase or lowercase?
- UUIDs are case-insensitive according to RFC 4122. The lowercase form (using a-f) is the canonical representation and is more common, but uppercase (A-F) is equally valid. Some systems or style guides prefer one over the other, so the option is provided for convenience.
- Can I generate UUIDs in bulk?
- Yes. You can generate up to 50 UUIDs at once using the count input. Each UUID appears in a list with its own copy button, and a bulk copy button lets you grab all of them at once separated by newlines.
- What is the difference between UUID versions?
- UUID v1 is based on the current timestamp and MAC address. UUID v3 and v5 are generated by hashing a namespace and a name with MD5 or SHA-1 respectively. UUID v4, which this tool generates, uses random data for all significant bits. UUID v7, a newer standard, combines a Unix timestamp with random data for sortable IDs.
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