UUID Generator

What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit value used to label data without a central authority handing out numbers. It is written as 32 hexadecimal characters split into five groups by hyphens, in the pattern 8-4-4-4-12, for example 550e8400-e29b-41d4-a716-446655440000. The standard is defined in RFC 4122 and updated by RFC 9562, which also introduced the newer UUID v6, v7 and v8 formats. Because UUIDs can be created anywhere, on any device, without checking a shared counter, they are used across web apps, mobile apps, distributed systems and databases.

How to Generate a UUID Online

1. Select the UUID version: v4 for a random UUID, v7 for a time-ordered UUID, v1 for a timestamp-based UUID, or Nil for the all-zero UUID.
2. Enter how many UUIDs you need: type any number from 1 to 1,000, or use the quick buttons.
3. Pick the output format: lowercase or UPPERCASE, with or without hyphens, plain, in { braces } or in "quotes".
4. Copy or download: use Copy for the clipboard or Download .txt to save a bulk list.

UUID Versions Explained: v1 vs v4 vs v7

Each UUID version builds the identifier in a different way. This table shows when to use which one.

UUID vs GUID: What Is the Difference?

There is no practical difference. GUID (Globally Unique Identifier) is the term used in Microsoft products such as .NET, C#, SQL Server and Windows, while UUID is the name used in the RFC standard and in most other languages and databases. Both are 128-bit identifiers with the same layout, so a GUID created here works anywhere a UUID is accepted, and the other way round. The only visible difference is style: GUIDs are often shown in uppercase or wrapped in curly braces.

Are UUIDs Really Unique? Collision Probability

A random UUID v4 has 122 random bits, which gives about 5.3 × 10³⁶ possible values. You would have to generate roughly one billion UUIDs every second for around 85 years before the chance of a single duplicate reached 50%. For real-world apps, the chance of a collision is so small that it is treated as impossible. The generator on this page uses crypto.getRandomValues(), a cryptographically secure source, instead of Math.random(), which is not suitable for unique IDs.

Using UUIDs as Database Primary Keys

UUIDs are popular as primary keys in MySQL, PostgreSQL and SQL Server because you can create IDs in your app before saving a record, merge data from several sources, and avoid exposing guessable numbers such as /users/1. The trade-off is index performance: fully random UUID v4 values are inserted at random positions, which can fragment indexes on large tables. UUID v7 solves this because the timestamp prefix makes new rows land at the end of the index, while keeping the benefits of a UUID. If you store UUIDs in MySQL, a BINARY(16) column uses less space than a CHAR(36) column.

How to Generate a UUID in Code

Need UUIDs inside your own project? These are the most common one-liners.

crypto.randomUUID()

use Illuminate\Support\Str;

Str::uuid();      // v4
Str::uuid7();     // v7

import uuid

uuid.uuid4()

Guid.NewGuid()

SELECT UUID();

SELECT gen_random_uuid();

Common Uses for a UUID Generator

• Database records: primary keys and foreign keys that are safe to create on the client or server.
• APIs and microservices: request IDs, correlation IDs and idempotency keys for tracing and retries.
• Testing and mock data: bulk lists of unique IDs for fixtures, seeders and load tests.
• File and upload names: collision-free names for images, documents and exports.
• Sessions and tokens: unique identifiers for sessions, invitations and one-time links (use a dedicated secret token for security-critical secrets).
• Windows and .NET: GUIDs for installers, COM components and registry entries.

Why Use Our Online UUID Generator?

Our UUID generator is built to be quick and private. It is free with no signup, creates up to 1,000 UUIDs per click, supports v4, v7, v1 and Nil, and lets you control case, hyphens and wrapping so the output matches your code or database. Because the work happens in your browser, your generated IDs are never uploaded or logged, and the tool works on desktop, tablet and mobile.