UUID Generator

Generate cryptographically secure UUID v4 values using the Web Crypto API.

Options
UUID v4 Format
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
  • 128-bit number represented as 32 hexadecimal characters
  • The 4th group starts with "4" indicating version 4 (random)
  • The 5th group starts with 8, 9, a, or b (variant bits)
  • Generated using cryptographically secure random numbers

What is UUID Generator?

A UUID Generator creates Universally Unique Identifiers (UUIDs) — standardized 128-bit values formatted as 32 hexadecimal digits in the pattern xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed to be globally unique without a central coordinating authority, meaning two independently generated UUIDs should never collide, even across different systems generating millions of UUIDs per second.

UUIDs are used throughout software development as primary keys in databases, identifiers for distributed system entities, unique file names, session tokens, correlation IDs in logging systems, and identifiers in APIs. The most common version is UUID v4, which is randomly generated, making collisions statistically impossible — there are 2^122 possible values, more than enough for any practical application.

The alternative to UUIDs in databases is auto-incrementing integer IDs, which are sequential and can expose information about record counts. UUIDs as IDs prevent this and work naturally in distributed systems where multiple database nodes need to generate IDs without coordination.

How to Use UUID Generator

  1. 1Step 1: Choose the UUID version you need. UUID v4 (random) is the most common choice for general use. UUID v1 is time-based and includes the machine's MAC address in the identifier.
  2. 2Step 2: Select how many UUIDs to generate if the tool supports batch generation. For database seeding, testing, or bulk operations you may need dozens or hundreds at once.
  3. 3Step 3: Click 'Generate' to create the UUID(s). Each UUID will be displayed in the standard 8-4-4-4-12 hyphenated format, such as 550e8400-e29b-41d4-a716-446655440000.
  4. 4Step 4: Copy the generated UUID(s) directly from the output. Most tools provide a one-click copy button for convenience when you only need a single UUID.
  5. 5Step 5: Use the UUID as a primary key in your database INSERT statement, as an identifier in your API payload, in your code for testing, or anywhere a globally unique identifier is required.

Benefits of Using UUID Generator

  • Global Uniqueness: UUIDs are statistically guaranteed to be unique across all space and time without any coordination between systems, making them ideal for distributed database architectures.
  • No Central Authority: Unlike auto-increment integers that require a database sequence, UUID v4 values can be generated anywhere — in the client, in microservices, or offline — without conflicts.
  • Hides Business Data: Using random UUIDs as record identifiers prevents users or competitors from inferring how many records exist in your database by observing sequential ID patterns.
  • API Idempotency: UUIDs are perfect idempotency keys for API requests, allowing clients to safely retry failed requests without risking duplicate operations on the server.
  • Instant Test Data: Quickly generate UUIDs for database seeding scripts, unit test fixtures, API mocking, or manual testing without needing to run application code.
  • Standard Format: UUIDs follow RFC 4122, meaning they are recognized and handled correctly by virtually all databases (PostgreSQL UUID type, MySQL CHAR(36)), programming languages, and APIs.

Example

A backend developer is writing database seed data for a new microservice that uses UUIDs as primary keys. They need to create 10 user records with known, fixed UUIDs so their integration tests can reference specific records. They generate 10 UUIDs from the UUID generator, copy them into a SQL seed script as the primary key values for INSERT statements, and reference those same UUIDs in their test assertions. Because the IDs are fixed in the seed data, tests can reliably look up specific records by ID, making tests deterministic and repeatable regardless of the order in which they run.

About UUID Generator

UUID Generator creates cryptographically random version 4 UUIDs suitable for use as unique identifiers in databases, APIs, and distributed systems. Generate one or a bulk batch of UUIDs and copy them as a list. All generation happens client-side.

  • RFC-compliant UUID v4 generation
  • Bulk generation of multiple UUIDs
  • Copy single or all UUIDs
  • Fully client-side, no server needed