What is UUID v4 Generator Online?
A Universally Unique Identifier (UUID) is a 128-bit label standardised by the IETF via RFC 4122. With 3.4×10³⁸ possible values, collisions are astronomically unlikely even at massive scale. This uuid generator online tool ensures your identifiers are unique and secure. Version 4 UUIDs are generated purely from random bytes — unlike Version 1 (time + MAC address), v4 provides no identifying metadata about the machine or timestamp, making them ideal for public-facing identifiers. All generation happens in your browser using the native browser-built-in `crypto.randomUUID()` API, so no data is ever sent to a server. This guarantees 100% privacy and security for your development workflow. Using a UUID as a primary key in distributed systems prevents conflicts that occur with auto-incrementing integers. It allows you to generate IDs on the client-side without a round-trip to the database, improving application performance and scalability.
How to Use UUID v4 Generator Online
- Choose the number of UUIDs to generate (1–100).
- Click "Regenerate" or press ⌘↵ to produce fresh UUIDs.
- Click any UUID to copy it instantly to your clipboard.
Example
A typical UUID v4 output
Output
550e8400-e29b-41d4-a716-446655440000Developer Tips
For high-performance database indexing, consider using PostgreSQL's native `uuid` type instead of `text` as it is significantly more storage-efficient (16 bytes vs 36+ bytes). If you need sortable IDs, check out ULIDs.
Frequently Asked Questions
Is UUID generation secure?
Yes. We use crypto.randomUUID() — a cryptographically strong API built into modern browsers. No data leaves your device.
What is the difference between UUID v1 and v4?
v1 encodes your MAC address and current timestamp, leaking identifiable information. v4 uses pure randomness — it is the industry default for safe, anonymous identifiers.
Can two UUID v4 values ever be the same?
Technically yes, but the probability is 1 in 5.3×10³⁶ — essentially impossible in practice.
Can I use this UUID in a database primary key?
Absolutely. UUID v4 is one of the most common primary key strategies in PostgreSQL, MySQL, and MongoDB.