UUID Generator | Free Online UUID Generator

Generate random UUIDs in batches with free online UUID generator, including UUID versions from v1 to v7.


Configuration

Specify UUID version.

Number between 1 and 100.

UUIDs in uppercase.

Enclose the UUIDs in quotes.

Put commas after each UUID.

Encode UUIDs in Base64.

How to Use UUID Generator

A step-by-step guide to generating UUIDs with our tool

1

Select UUID Version

Choose the UUID version you need from the available options (v1 to v7). Each version has different characteristics and use cases. Refer to the UUID Versions section for more information.

2

Configure Number of UUIDs

Configure how many UUIDs you want to generate. You can generate up to 100 UUIDs at once.

3

Set Output Format Options

Customize the format of your generated UUIDs by selecting from the available options.

4

Provide Namespace and Name (for v3 and v5)

If you selected v3 or v5 (Name-Based UUIDs), you need to provide a predefined namespace (DNS, URL, OID, X.500) and a name.

5

Generate UUIDs

UUIDs will be automatically generated based on the configuration.

UUID Versions Explained

Learn about the different UUID versions and their use cases

v1

Version 1 (Time-Based)

Generated from a timestamp and MAC address. Guarantees uniqueness but may reveal temporal and spatial information.

  • Based on timestamp and MAC address
  • Globally unique
  • Not cryptographically secure
  • May reveal device information
v2

Version 2 (DCE Security)

Similar to v1 but includes POSIX UID/GID information. Rarely used outside of legacy systems.

  • Based on timestamp, MAC address, and UID/GID
  • Used in DCE security applications
  • Less common than other versions
  • Not supported by all UUID libraries
v3

Version 3 (Name-Based)

Generated from a namespace UUID and a name using MD5 hashing. Deterministic (same input produces same UUID).

  • Uses MD5 hashing
  • Deterministic
  • Not cryptographically secure
  • Use v5 instead for modern applications
v4

Version 4 (Random)

Generated using cryptographically secure random numbers. Most commonly used UUID version for general purposes.

  • Uses secure random number generation
  • High probability of uniqueness
  • Cryptographically secure
  • Recommended for most use cases
v5

Version 5 (Name-Based)

Similar to v3 but uses SHA-1 hashing. More secure than v3 and recommended for name-based UUIDs.

  • Uses SHA-1 hashing
  • Deterministic
  • More secure than v3
  • Recommended for name-based UUIDs
v6

Version 6 (Reordered Time)

A new version that reorders the v1 timestamp to improve database performance while maintaining temporal order.

  • Reordered v1 timestamp
  • Improves database performance
  • Maintains temporal order
  • Backward compatible with v1
v7

Version 7 (Unix Epoch Time)

Uses Unix epoch time for better interoperability with other systems and improved entropy.

  • Based on Unix epoch time
  • Improved entropy
  • Interoperable with other systems
  • Recommended for new applications

Frequently Asked Questions

Find answers to common questions about UUIDs

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit number used to identify information in computer systems. UUIDs are designed to be unique across both space and time, with a very low probability of collision.

The choice of UUID version depends on your use case:

  • Use v4 (Random) for most general purposes where randomness and uniqueness are required.
  • Use v5 (Name-Based) if you need deterministic UUIDs generated from a name and namespace.
  • Use v1 (Time-Based) if you need time-ordered UUIDs or require backward compatibility with legacy systems.
  • Consider v7 (Unix Epoch Time) for new applications requiring time-ordering and interoperability.

The security of a UUID depends on its version:

  • v4 (Random) uses cryptographically secure random number generators, making it suitable for security-sensitive applications like tokens or secrets.
  • v1 (Time-Based) and v2 (DCE Security) are not cryptographically secure as they are based on timestamps and MAC addresses.
  • v3 (MD5) and v5 (SHA-1) are deterministic and not intended for security purposes but for generating predictable UUIDs from names.

For security-critical applications, use v4 UUIDs and ensure proper entropy sources.

Each UUID version has a different generation mechanism:

  • v1: Based on timestamp and MAC address
  • v2: Similar to v1 but includes POSIX UID/GID information
  • v3: Name-based using MD5 hashing
  • v4: Randomly generated using cryptographically secure random numbers
  • v5: Name-based using SHA-1 hashing
  • v6: Reordered v1 timestamp for better database performance
  • v7: Based on Unix epoch time for interoperability

See the UUID Versions section for detailed comparisons.

While no system can provide absolute certainty, UUIDs are designed to have an extremely low probability of collision. For example:

  • v4 UUIDs have 122 bits of randomness, giving a collision probability of about 1 in 2^122 (or approximately 5.3x10^36).
  • To put this in perspective, generating 1 billion UUIDs per second for 100 years would still result in a collision probability of less than 1 in 1,000,000.

For practical purposes, UUIDs can be considered unique.