UUID / GUID Generator Online
Generate secure, cryptographically random UUID v4 and time-based UUID v1. Bulk generate up to 1000 UUIDs. 100% private - runs in browser.
What is UUID?
UUID (Universally Unique Identifier) also called GUID is 128-bit unique ID. Example: 550e8400-e29b-41d4-a716-446655440000
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What is a UUID / GUID Generator?
A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier) in Microsoft systems, is a 128-bit identifier. It is written as 32 hexadecimal characters in an 8-4-4-4-12 pattern, for example 550e8400-e29b-41d4-a716-446655440000. The chance of two randomly generated UUIDs colliding is so small that they are treated as unique in practice.
This free generator creates UUID v4 (random) and UUID v1 (time-based) directly in your browser. UUID v4 uses the browser's Web Crypto API (crypto.randomUUID()), which is cryptographically strong, unlike Math.random(). You can generate one UUID or up to 1000 at once for testing, seeding databases or creating mock data.
UUID v1 vs v4
| Version | How it is made | Predictable? | Best for |
|---|---|---|---|
| v4 | 122 random bits | No | API keys, session IDs, primary keys, general use |
| v1 | Timestamp + node ID | Yes, partly | Legacy systems that need a time component |
Supported Output Formats
| Format | Example | Commonly used in |
|---|---|---|
| Lowercase (default) | 550e8400-e29b-41d4-a716-446655440000 | JavaScript, Linux, Python, .NET |
| Uppercase | 550E8400-E29B-41D4-A716-446655440000 | Some databases and legacy systems |
| Without hyphens | 550e8400e29b41d4a716446655440000 | Compact storage, file names |
| Braces (GUID) | {550e8400-e29b-41d4-a716-446655440000} | Windows Registry, COM, C# |
How to Use the UUID Generator
- Select the UUID version (v4 is recommended for most cases).
- Enter the quantity, from 1 to 1000.
- Choose the output format.
- Click Generate UUID.
- Click Copy All or Download as TXT.
Privacy
All UUIDs are generated locally in your browser. Nothing is sent to a server or stored, and the tool keeps working offline after the page loads.
Frequently Asked Questions
What is the difference between UUID and GUID?
They are the same 128-bit identifier. UUID is the standard name used in Linux, JavaScript and Python. GUID is the name Microsoft uses in Windows and .NET. GUIDs are often written inside braces, for example {550e8400-e29b-41d4-a716-446655440000}.
Which UUID version should I use, v1 or v4?
Use v4 for most use cases. It is random and unpredictable. Use v1 only if an existing system needs a time-based UUID. Note that v1 is predictable and its text form does not sort by creation time.
Is this UUID generator secure and private?
UUID v4 is generated with the browser's Web Crypto API, which is cryptographically strong. Everything runs locally in your browser and nothing is sent to a server.
Can I generate UUIDs in bulk?
Yes. Enter a quantity from 1 to 1000, click Generate UUID, then copy all results or download them as a TXT file.
Are UUIDs really unique?
Not mathematically guaranteed, but the collision probability of random v4 UUIDs is so small that they are safe to use as unique identifiers in practice.