UUID generator
Generate up to 1,000 random version 4 UUIDs at once with crypto.randomUUID. Choose lowercase, uppercase or no hyphens, then copy or download the list.
About UUID generator
The UUID generator creates random version 4 UUIDs, the 128-bit identifiers also known as GUIDs, using the browser’s crypto.randomUUID function and its cryptographically secure random number generator. Ten are generated when the page opens, and you can produce anywhere from 1 to 1,000 at a time.
Choose standard lowercase output, uppercase for systems that display GUIDs that way, or a 32-character form without hyphens for compact keys and file names. Each UUID is on its own line, ready to paste into a seed script, spreadsheet or test fixture.
How to use UUID generator
- Enter how many UUIDs you need in the Count field, from 1 to 1,000.
- Choose Lowercase, Uppercase or No hyphens.
- Select Generate to create a new batch at any time.
- Copy the list or download it as a .txt file.
Features
- Generates version 4 UUIDs as defined in RFC 9562, with 122 random bits each.
- Uses crypto.randomUUID, backed by a cryptographically secure random source.
- Creates 1 to 1,000 UUIDs per batch, one per line.
- Outputs lowercase, uppercase or 32-character hex without hyphens.
- Generates a fresh batch automatically when you change the count or format.
Common uses
- Creating primary keys or seed data for a database.
- Filling test fixtures and mock API responses with unique IDs.
- Generating request or correlation IDs to test logging and tracing.
- Naming files, uploads or cache entries without collisions.
Frequently asked questions
What is the difference between a UUID and a GUID?
They are the same 128-bit identifier format. UUID is the name used in the RFC standards; GUID is Microsoft’s term. GUIDs are often shown in uppercase, sometimes inside braces, but the value is identical.
Can two version 4 UUIDs collide?
In theory yes, in practice no. A v4 UUID has 122 random bits, so you would need about 2.7 quintillion UUIDs for a 50% chance of a single duplicate. Collisions in real systems almost always come from a broken random source, not from the format.
What is the difference between UUID v4 and v7?
Version 4 is entirely random. Version 7 starts with a millisecond timestamp, so values sort by creation time, which helps database index performance. This tool generates version 4 only; use v7 when ordering matters and your database or library supports it.
Are uppercase UUIDs or UUIDs without hyphens still valid?
The standard recommends lowercase output and case-insensitive parsing, so uppercase UUIDs are accepted by most systems. The 32-character form without hyphens holds the same value and is accepted by many databases and libraries, but check that your target system supports it before storing it that way.
Can I use UUIDs as secret tokens?
They come from a secure random source, but UUIDs are designed to be unique, not secret, and often appear in URLs and logs. For API keys, password reset links or session tokens, use the random string generator with a longer length.
Is my input uploaded?
Tools run in your browser. Files, text and results are not uploaded to our servers and are cleared when you leave the tool.
Your privacy comes first
Tools run in your browser. Files, text and results are not uploaded to our servers and are cleared when you leave the tool.