UUID v4 Generator
Generated in your browser — never sent to a server.
What is UUID v4 Generator
UUID v4 (Universally Unique Identifier version 4) is a 128-bit random identifier in the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. This generator uses the browser's native Web Crypto API to produce cryptographically secure UUIDs with no server involved. UUID v4 is the most widely used UUID version because it requires no coordination, no network access, and no shared state.
How to use
- Select the number of UUIDs to generate from the Quantity menu.
- Click Generate or change the quantity to produce a fresh batch.
- Click Copy next to any UUID to copy it individually to your clipboard.
- Click Copy all to copy the full list as newline-separated values.
Use cases
A developer building a distributed system needs unique IDs for events. They generate a batch of 25 UUID v4 values here and paste them directly into fixture files or INSERT statements, where each event needs a pre-assigned unique identifier before the database is even touched.
Frequently asked questions
Are these UUIDs truly unique?
UUID v4 uses 122 bits of randomness, giving a collision probability of roughly 1 in 5.3 × 10³⁶. For all practical purposes, collisions are impossible.
What is the UUID v4 format?
UUID v4 follows xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is a random hex digit and y is 8, 9, a, or b. The '4' in the third group marks it as version 4.
Are my UUIDs sent to a server?
No. All generation happens locally in your browser using the native Web Crypto API (crypto.randomUUID). Nothing is ever transmitted.
Can I use UUID v4 in a database?
Yes. UUID v4 is natively supported in PostgreSQL (uuid type), MySQL 8+ (UUID() function), SQL Server (UNIQUEIDENTIFIER), and stored as a string in MongoDB.
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