UUID v4 Generator — Free Online UUID / GUID Tool

How to use

1. Set Quantity — Choose how many UUIDs to generate (1–100)
2. Generate — Click Generate or adjust the count to create new UUIDs
3. Copy — Copy all UUIDs to your clipboard

What Is a UUID?

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier) in Microsoft ecosystems, is a 128-bit number used to uniquely identify information in computer systems. The standard format is 32 hexadecimal digits separated by hyphens into five groups: 8-4-4-4-12.

UUIDs solve a fundamental problem in distributed computing: how to create unique identifiers without a central coordination point. Each UUID is generated independently and is statistically guaranteed to be unique across all devices, all time.

UUID Versions Explained

There are five standard UUID versions, each using a different generation method:

• Version 1: Based on timestamp and MAC address. Unique but reveals machine identity.
• Version 2: DCE Security version. Rarely used in modern applications.
• Version 3: Generated from MD5 hash of a namespace and name. Deterministic.
• Version 4: Randomly generated. Most widely used. This tool generates V4.
• Version 5: Generated from SHA-1 hash of a namespace and name. Deterministic.

Why Use UUIDs?

UUIDs offer several advantages over sequential integer IDs:

• No coordination needed: Multiple servers can generate IDs without checking a central database
• Merge-friendly: Databases from different sources can be merged without ID conflicts
• Security: Random UUIDs don't reveal record count or creation order
• URL-safe: UUIDs work well in URLs and file paths

UUID v4 Randomness

Version 4 UUIDs contain 122 bits of randomness. This means there are approximately 5.3 × 10^36 possible UUIDs. To put this in perspective, if you generated one billion UUIDs per second, it would take about 100 years to have a 50% probability of creating a single duplicate.

Privacy

UUIDs are generated using your browser's crypto.randomUUID() function. No data is sent to any server.

Need random strings instead? Try our Random String Generator. For secure passwords, check our Password Generator.

Frequently asked questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hexadecimal digits displayed in five groups separated by hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are designed to be unique without requiring a central authority.

What version of UUID does this generate?

This tool generates Version 4 UUIDs, which are randomly generated. V4 UUIDs use 122 random bits, giving approximately 5.3 × 10^36 possible values — making collisions virtually impossible.

Can two UUIDs ever be the same?

Theoretically yes, but practically no. The probability of generating a duplicate UUID v4 is astronomically low — you would need to generate about 2.71 quintillion UUIDs to have a 50% chance of one collision.

Where are UUIDs commonly used?

UUIDs are used as database primary keys, session identifiers, API request IDs, distributed system identifiers, file names, and transaction IDs. They're especially useful in systems where multiple nodes need to generate IDs independently.

Are these UUIDs generated securely?

Yes. This tool uses crypto.randomUUID() which relies on the browser's cryptographically secure random number generator.

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