UUID Generator
Generate cryptographically random UUID v4 values in bulk — standard, uppercase, no-hyphens, or braces format.
Click Generate to create cryptographically random UUID v4 values using your browser's built-in crypto.randomUUID(). No data is sent to any server.
What is UUID Generator?
UUID Generator creates UUID v4 values using your browser's cryptographically secure random number generator (`crypto.randomUUID()`). Generate 1 to 100 UUIDs at once in any format — standard lowercase with hyphens, uppercase, stripped hyphens, or wrapped in braces.
UUIDs (Universally Unique Identifiers) are 128-bit values with 2¹²² possible combinations, making collisions astronomically unlikely. They are used as primary keys in databases, request correlation IDs, file names, API tokens, and anywhere a unique identifier is needed without a central issuing authority.
Common Use Cases
- Generating primary key values for database inserts during development
- Creating unique file names for uploaded assets to avoid collisions
- Producing correlation IDs for distributed system request tracing
- Generating test fixture IDs for unit and integration tests
- Creating unique session tokens or temporary identifiers
How to Use UUID Generator
- Select how many UUIDs to generate using the preset count buttons or type a custom number.
- Choose a format: Standard, Uppercase, No hyphens, or Braces.
- Click Generate UUIDs, then copy individual values or all at once.
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FAQ
What is a UUID and what is it used for?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardised in RFC 4122. UUID v4 is randomly generated, making it statistically impossible to collide with another UUID. UUIDs are used as database primary keys, unique file names, API resource identifiers, and session tokens — anywhere a unique, collision-resistant ID is needed without a central authority.
What is the difference between a UUID and a GUID?
GUID (Globally Unique Identifier) is Microsoft's name for the same concept. GUIDs and UUIDs follow the same RFC 4122 standard and are interchangeable. The term UUID is more common in Unix/Linux and database contexts; GUID is more common in Windows and .NET environments.
Is UUID v4 truly unique?
UUID v4 has 122 bits of randomness, giving 5.3 × 10³⁶ possible values. The probability of generating a duplicate in 1 billion UUIDs per second for 100 years is still astronomically small. For all practical purposes, UUID v4 values are unique — collisions are a theoretical concern, not a practical one.
Are the generated UUIDs cryptographically secure?
Yes — the generator uses `crypto.randomUUID()`, which is backed by the browser's cryptographically secure pseudo-random number generator (CSPRNG). This is the same entropy source used for cryptographic operations. No data is sent to a server.
When should I use UUID v4 vs UUID v7?
UUID v4 is fully random and ideal when ordering does not matter. UUID v7 (a newer standard) embeds a millisecond timestamp prefix, making it sortable by creation time — better for database index performance. If you are inserting UUIDs as primary keys into a B-tree index at high volume, UUID v7 avoids the index fragmentation that random v4 UUIDs cause.