UUID / GUID Generator

What this tool does

A UUID (Universally Unique Identifier, also called a GUID) is a 128-bit value used as a unique ID for database rows, API keys, session tokens, distributed system records — anywhere you need an identifier that's statistically guaranteed not to collide, without a central authority handing out sequential numbers. This tool generates them in your browser using the Web Crypto API's cryptographically secure random number generator, in bulk, formatted exactly how your code needs them.

How to use it

• Pick Version 4 for the standard fully-random UUID (the one almost every codebase actually wants), Version 1 for a time-based UUID that encodes a timestamp, or Nil UUID for the reserved all-zeros placeholder value.
• Set how many you need — up to 1,000 at once.
• Toggle uppercase, hyphens, curly braces (the classic Windows/.NET GUID format), or a urn:uuid: prefix to match whatever your code or config expects.
• Click Generate, then copy all or download the full list as a .txt file.

Real-world use cases

• Seeding test/mock data with realistic-looking unique IDs before a database's auto-increment logic is wired up.
• Generating a batch of API keys, request IDs, or idempotency keys for a script or Postman collection.
• Getting a GUID in the {8-4-4-4-12} braced format that .NET and older Windows APIs expect.
• Creating unique element IDs or feature-flag keys during frontend development.

Frequently asked questions

What's the difference between a UUID and a GUID?

They're the same thing in practice — GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit format defined by the UUID standard, RFC 4122. Any UUID generated here works as a GUID too.

Should I use version 1 or version 4?

Use version 4 unless you specifically need the timestamp encoded in the ID itself. Version 4 is fully random and is what almost every modern system (databases, APIs, session tokens) actually means when it says "UUID." Version 1 embeds the generation time and a node identifier, which can leak information about when and where an ID was created — this tool randomizes the node id since browsers can't read a real MAC address, matching how most privacy-conscious v1 implementations already behave.

Are these UUIDs actually unique?

Version 4 UUIDs have 122 random bits, generated here with the Web Crypto API's cryptographically secure random source (not Math.random()). The odds of a collision are astronomically small — you'd need to generate billions of UUIDs per second for centuries before a collision became statistically likely.

Is anything sent to a server?

No — every UUID is generated entirely in your browser using the Web Crypto API. Nothing is transmitted or logged anywhere.