Generate random version 4 UUIDs with the browser's native crypto API — one or many, instantly.
1 to 50. Runs in your browser — nothing is uploaded.
1 UUID · version 4
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label written as 32 hex digits in five groups separated by hyphens: 8-4-4-4-12 characters, for example a3f2c1d4-7e80-4b2a-9f31-0c5d8e6a1b72. Version 4 — the most common kind — fills 122 of those bits with random data, making collisions so unlikely they are not worth engineering around at any realistic scale. This tool calls crypto.randomUUID(), the browser's native cryptographically secure random number generator, so the output is as random as your operating system can produce. No request leaves your browser; the generator has no knowledge of any UUID it has produced before. UUIDs from this tool are suitable for database primary keys, API resource identifiers, session tokens, and test fixtures — anywhere you need a unique label without a central registry.
How to use the UUID generator
Set the count. Use the stepper to choose how many UUIDs you need — from 1 up to 50. The default is 1.
Click Generate. Click the Generate button. A new set of version 4 UUIDs appears in the output panel instantly. Each click produces a fresh batch; previous results are replaced.
Copy what you need. Click the inline Copy button next to any single UUID to copy just that one, or click Copy all to put the entire list on your clipboard at once.
Frequently asked questions
What is a UUID and what is it used for?
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as five hyphen-separated groups of hex digits, for example a3f2c1d4-7e80-4b2a-9f31-0c5d8e6a1b72. UUIDs are used as primary keys in databases, resource identifiers in REST APIs, file names for uploads, and unique labels in distributed systems — anywhere you need a unique ID without coordinating with a central counter.
What is the difference between UUID v4 and other versions?
UUID v1 is based on the current timestamp and the device's MAC address, which can leak information about when and where it was generated. UUID v5 derives a deterministic UUID from a name and a namespace using SHA-1 hashing — useful when you want the same input to always produce the same UUID. UUID v4 is purely random (122 random bits, 6 bits fixed for the version and variant fields), which makes it the safest choice when you have no special requirement for the other versions.
Are UUIDs generated here truly random?
Yes. This tool calls crypto.randomUUID(), which is part of the Web Crypto API and reads randomness from the operating system's cryptographically secure pseudo-random number generator (CSPRNG) — the same source used for cryptographic keys. No UUID is generated on a server; nothing is logged or transmitted.
Can two UUIDs ever be the same?
In theory, yes — UUID v4 has 122 random bits, giving 2^122 possible values. In practice, generating a duplicate is so unlikely that it has no bearing on any real system. The birthday bound puts the 50% collision threshold at roughly 2.71 × 10^18 UUIDs. At a rate of one billion UUIDs per second that would take about 85 years.
Is a UUID the same as a password or secret key?
No. A UUID v4 is an identifier, not a secret. While it is randomly generated, it is typically stored in databases, passed in URLs, and logged in plain text. Do not use a bare UUID as an authentication secret or API key without additional security controls. For secrets, use a dedicated key-generation approach with the appropriate bit length and storage policy.