UUID v4 Generator
This tool generates cryptographically random UUID version 4 identifiers in your browser using the native crypto.randomUUID() API.
What is UUID v4 Generator?
A UUID (Universally Unique Identifier) is a 128-bit label standardized by RFC 4122, formatted as 32 hexadecimal digits in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUID version 4 (UUIDv4) is randomly generated, meaning there is no embedded timestamp, MAC address, or namespace — it is pure random data. With 2^122 possible values (approximately 5.3 undecillion), the probability of generating a duplicate UUID v4 in a system with one billion UUIDs per second for 100 years is roughly 50% — an effectively impossible collision in practice for any real-world application.
How to use UUID v4 Generator
- Click 'Generate' to produce a single UUID v4 instantly.
- Set the quantity field to generate multiple UUIDs at once (up to 100).
- Choose uppercase or lowercase format for the hex characters.
- Click 'Copy All' to copy every generated UUID to your clipboard.
- Use the generated UUIDs as primary keys in databases, correlation IDs in logs, or client-side resource identifiers.
UUID v4 Generator Example
Generate 1 UUID v4
a3bb189e-8bf9-3888-9912-ace4e6543002
Frequently Asked Questions
What are the different UUID versions?
UUID v1 uses the MAC address and timestamp (predictable). UUID v3/v5 use namespace-based MD5/SHA-1 hashing (deterministic). UUID v4 (this tool) is fully random. UUID v7, introduced in 2022, combines a random component with a millisecond-precision timestamp, making it both unique and sortable.
Can two generated UUIDs ever be the same?
Theoretically yes, but the probability is astronomically small. You would need to generate approximately 2.71 quintillion UUIDs before reaching a 50% chance of a single collision.
Should I use a UUID as a database primary key?
Yes, but with caveats. UUIDv4 is non-sequential, which can cause index fragmentation in B-tree indexes. For high-write databases, consider UUIDv7 (sortable) or a ULID as a more performant alternative.
Is the UUID generated here truly random?
Yes. This tool uses the browser's crypto.randomUUID() method which calls the operating system's CSPRNG (Cryptographically Secure Pseudo-Random Number Generator), not the weaker Math.random().
Does this tool store or log generated UUIDs?
No. UUID generation happens entirely client-side in your browser. No data is sent to our servers.