UUID Generator
Generate random UUID v4 or time-ordered UUID v7 identifiers — one or a thousand at a time — from your browser’s cryptographic random number generator.
How to generate UUIDs
Choose a version
Use v4 for fully random IDs, or v7 when you want IDs that sort by creation time — ideal for database primary keys.
Set the quantity and format
Generate between 1 and 1,000 at once. Toggle uppercase, hyphens or braces, and pick plain lines, a JSON array, CSV or an SQL list.
Copy or download
Copy a single UUID from its row, copy the whole batch, or download it as a text file for seed data and fixtures.
What is a UUID?
A UUID (universally unique identifier), also called a GUID in Microsoft ecosystems, is a 128-bit value written as 32 hexadecimal digits in five groups: 8-4-4-4-12. UUIDs let independent systems create identifiers without a central counter, so you can generate IDs on the client, in a queue worker or across database shards without collisions.
UUID v4 vs UUID v7
| UUID v4 | UUID v7 | |
|---|---|---|
| Source | 122 random bits | 48-bit Unix millisecond timestamp + 74 random bits |
| Sortable by time | No | Yes — lexical order matches creation order |
| Database index locality | Poor (random inserts) | Good (append-mostly B-tree inserts) |
| Leaks creation time | No | Yes, to the millisecond |
| Specification | RFC 9562 (formerly RFC 4122) | RFC 9562 |
This generator uses crypto.randomUUID() for v4 where available and crypto.getRandomValues() otherwise. Version 7 IDs created in the same millisecond use a monotonic counter, so a batch is always in ascending order.
Can two UUIDs collide?
In practice, no. With 122 random bits, you would need to generate about 2.7 quintillion v4 UUIDs to reach a 50% chance of a single duplicate. The real risks are poor random number generators and copy-paste mistakes — not the format itself.
Frequently asked questions
Are these UUIDs cryptographically secure?
Yes. Every random bit comes from the browser’s Web Crypto API (crypto.randomUUID() or crypto.getRandomValues()), never Math.random(). Nothing is sent to a server.
Should I use UUID v4 or v7 for database primary keys?
Prefer UUID v7 for primary keys. Because v7 starts with a timestamp, new rows land at the end of the index instead of random positions, which reduces page splits and improves insert performance in PostgreSQL, MySQL and SQL Server. Use v4 when you don’t want the creation time to be visible.
What is the difference between a UUID and a GUID?
They are the same 128-bit format. “GUID” is Microsoft’s name and is often written in uppercase inside braces, like {3F2504E0-4F89-41D3-9A0C-0305E82C3301}. Turn on Uppercase and Braces to produce that style.
How many UUIDs can I generate at once?
Up to 1,000 per batch. Copy them all, download them as a text file, or output them as a JSON array, CSV or SQL list.
How do I validate a UUID or read its timestamp?
Paste it into the Inspect a UUID box. It checks the format and reports the version and variant. For v7 (and v1/v6) UUIDs it also decodes the embedded creation time.