Free UUID Generator Online

What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier) in Microsoft systems, is a 128-bit value used to label something uniquely without a central authority handing out IDs. It is standardized by RFC 4122 (and its successor RFC 9562). A UUID is usually written as 32 hexadecimal digits split into five groups by hyphens, in the pattern 8-4-4-4-12, for example 3f1a7c2e-9b4d-4e6a-8f21-0c9b7d5e4a13.

The point of a UUID is that any two parties can each generate one independently - on different machines, offline, at the same instant - and be confident the values won't collide. That makes UUIDs ideal for database primary keys, distributed systems, message IDs, file names, API request identifiers, and anywhere you need a unique key without coordinating with a server.

UUID versions explained

The version number lives in the 13th hex digit and tells you how the UUID was generated. This tool produces the three you'll use most often:

UUID v4 - random

Version 4 is generated almost entirely from random (here, cryptographically secure) data, with only the version and variant bits fixed. It's the most widely used version because it carries no information about the machine or time that produced it, making it the safest default for privacy. With 122 random bits there are roughly 5.3 × 10³⁶ possible values, so accidental collisions are, for all practical purposes, impossible.

UUID v1 - time + node based

Version 1 combines the current timestamp (in 100-nanosecond intervals since 1582) with a clock sequence and a node identifier. Traditionally the node was the machine's MAC address; because that can leak hardware identity, this tool uses a random, locally-administered node instead. v1 values are roughly time-ordered, which can be useful, but the random-node variant is generally preferable to v4 only when you specifically need timestamp embedding.

UUID v7 - time-ordered

Version 7 is the modern choice for database keys. It puts a 48-bit Unix millisecond timestamp at the front, followed by random bits. Because the leading bits increase over time, v7 UUIDs sort in roughly chronological order - which keeps database indexes (especially B-tree primary keys) compact and fast, avoiding the index fragmentation that random v4 keys can cause, while still being globally unique.

Which version should you use?

• General-purpose unique IDs: use v4. It's the safe, private default.
• Database primary keys at scale: prefer v7 for index locality and time ordering.
• Legacy systems or when you need embedded timestamps: v1 may be required for compatibility.

Are these UUIDs safe and unique?

Yes. This generator runs entirely in your browser and uses the Web Crypto API (crypto.getRandomValues()) as its randomness source, so the random portions are cryptographically strong rather than predictable. Nothing you generate is sent to a server or logged. For v4 and v7, the probability of generating a duplicate is so small it can be ignored even across billions of values - you would need to generate around a billion UUIDs every second for roughly 85 years to have even a 50% chance of a single collision.

How to use this UUID generator

1. Choose the version you need (v4, v1, or v7) from the dropdown.
2. Set a quantity from 1 to 100 to generate a batch at once.
3. Click Generate, then copy the results or download them as a .txt file.

Bulk generation is handy for seeding test data, pre-allocating keys, or filling a fixtures file. Because everything happens locally, you can generate as many batches as you like with no rate limits.