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UUID Generator — Generate UUID v4 Online Free

Generate cryptographically secure UUID v4 identifiers online. Customize count, uppercase, and dash options. Copy all UUIDs with one click. 100% free, no sign-up.

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Free UUID v4 Generator Online

OptiDrop's UUID Generator creates cryptographically secure UUID v4 identifiers using the browser's built-in crypto.getRandomValues API. You can generate up to 100 UUIDs at once, choose uppercase or lowercase formatting, and include or exclude dashes. All generation happens locally in your browser.

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information. The standard format is 32 hexadecimal characters in five groups separated by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The '4' in the third group indicates it is a version 4 (random) UUID.

Why Use UUIDs?

UUIDs are essential in distributed systems, databases, and APIs where unique identifiers are needed without a central coordinating authority. They are commonly used as primary keys in databases, session tokens, transaction IDs, and file naming. The chance of generating two identical UUIDs is essentially zero.

Frequently Asked Questions

A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify information in computer systems. UUIDs are formatted as 32 hexadecimal digits displayed in five groups separated by hyphens, like 550e8400-e29b-41d4-a716-446655440000. They are designed to be globally unique without requiring a central authority.
UUID v4 is a randomly generated UUID. Unlike other UUID versions that use timestamps or names, v4 UUIDs are generated using random or pseudo-random numbers. This makes them ideal for situations where you need a unique identifier but don't need it to be deterministic or time-based. The '4' indicates the version and variant bits are set accordingly.
UUID v4 uses 122 random bits out of 128 total bits (6 bits are reserved for version and variant). This provides approximately 5.3 x 10^36 possible unique values. The probability of generating two identical UUID v4 values is astronomically low — you would need to generate about 2.71 quintillion UUIDs to have a 50% chance of a collision.
UUIDs are commonly used as primary keys in databases, session identifiers, transaction IDs, file names for uploaded files, API request IDs, and any situation where you need a unique identifier that can be generated independently without coordination. They are especially useful in distributed systems where multiple nodes need to generate unique IDs without a central authority.

Last updated: June 2026