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UUID Generator

Generate random UUID v4 identifiers. Bulk generate up to 100 at once.

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UUID Generator

Generate random UUID v4 identifiers. Bulk generate up to 100 at once.
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How to Use UUID Generator

  1. 1

    Set your options

    Choose the number of UUIDs to generate (1-100), and toggle hyphenation or uppercase as needed.

  2. 2

    Generate UUIDs

    Click the Generate button to create your UUIDs using the browser's cryptographically secure random number generator.

  3. 3

    Copy results

    Hover over any UUID to copy it individually, or click Copy All to copy the entire list.

Frequently Asked Questions

UUID v4 (Universally Unique Identifier version 4) is a 128-bit identifier generated using random or pseudo-random numbers. The format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is a random hex digit and y is one of 8, 9, a, or b.

Yes. This tool uses crypto.randomUUID(), which is backed by the browser's cryptographically secure pseudo-random number generator (CSPRNG).

Yes. Uncheck the Hyphenated option to generate UUIDs without dashes, which is useful for database primary keys or compact identifiers.

You can generate up to 100 UUIDs at once. All generation happens instantly in your browser.

Practically, no. UUID v4 provides 122 bits of randomness, yielding roughly 5.3 x 10^36 possible values. The probability of collision is astronomically low.

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UUID Versions and When to Use Each

UUID v4 (random) is the most widely used version, but it is not the only one. UUID v1 is time-based, encoding the timestamp and MAC address — useful for ordering but a privacy concern. UUID v5 is name-based (SHA-1 hash of a namespace + name), producing deterministic output for the same input. The newer UUID v7 (RFC 9562, 2024) combines a Unix timestamp prefix with random bits, giving you both time-ordering and uniqueness — increasingly preferred for database primary keys.

UUIDs as Database Primary Keys

UUIDs as primary keys enable distributed ID generation without coordination — any client or server can generate a unique ID independently. The downside is performance: random UUIDs (v4) cause B-tree index fragmentation because insertions land at random positions. UUID v7 solves this by being time-ordered, so new records cluster at the end of the index like auto-increment integers. If you use UUID v4, consider adding a separate auto-increment column for the clustered index.

Collision Probability in Practice

UUID v4 has 122 random bits, yielding 5.3 x 10^36 possible values. To have a 50% chance of a single collision, you would need to generate approximately 2.7 x 10^18 (2.7 quintillion) UUIDs — equivalent to generating 1 billion UUIDs per second for 86 years. In any realistic application, UUID v4 collisions are not a practical concern. The bigger risk is implementation bugs (using Math.random instead of crypto.getRandomValues) that reduce the actual entropy.