🆔 UUID Generator
Generate one or many random UUID v4 identifiers using the browser's cryptographically secure random number generator.
How to Use the UUID Generator
The UUID Generator creates one or many random UUID version 4 identifiers instantly in your browser. Enter the number of UUIDs you need in the Count field (from 1 to 100) and click Generate UUIDs. All generated UUIDs appear in the output box, one per line. Click Copy All to copy the entire list to your clipboard, then paste them into your code, database seed file, or spreadsheet.
UUID v4 identifiers are randomly generated 128-bit values formatted as 32 hexadecimal characters arranged in the pattern xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where 4 indicates version 4 and y is one of 8, 9, a, or b. This tool uses the browser's built-in crypto.randomUUID() method, which uses cryptographically secure randomness. UUIDs are used as database primary keys, session identifiers, message queue IDs, distributed system record identifiers, and anywhere you need a unique identifier without a central authority to assign sequential IDs.
Frequently Asked Questions
What is a UUID?
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A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit number used to identify information in computer systems. The standard representation uses 32 hexadecimal characters in the format 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are designed to be globally unique without requiring a central authority to assign them.
What is UUID version 4?
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UUID v4 is randomly generated — 122 of its 128 bits are random, with 6 bits reserved for the version and variant identifiers. It is the most commonly used UUID version and has no dependency on timestamps, MAC addresses, or any external system. The probability of generating the same UUID v4 twice is astronomically small (around 1 in 5.3 × 10³⁶).
When should I use a UUID as a primary key?
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UUIDs are useful as primary keys when: you need IDs that are safe to expose in URLs (they reveal no information about the order of records), you are merging data from multiple databases without ID conflicts, you need to generate IDs on the client before inserting into the database, or you are building a distributed system. The trade-off is that UUIDs use more storage (16 bytes vs 4–8 bytes for integers) and can hurt database index performance at very large scale.
Is a UUID truly unique?
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In practice, yes. UUID v4 has 2¹²² ≈ 5.3 × 10³⁶ possible values. If you generated 1 billion UUIDs per second for 100 years, the probability of a collision would still be less than 1 in a quintillion. For all practical purposes, UUID v4 can be considered unique without any coordination mechanism.