UUID Generator
Generate universal unique identifiers v4, instantly.
What it's for
Guaranteed unique UUIDs in milliseconds
RFC 4122 standard
UUIDs conforming to the international standard, compatible with any database, language, or framework.
100% private
UUIDs are generated in your browser. No identifier is sent to or logged on our servers.
Cryptographic randomness
Uses crypto.getRandomValues() to ensure each UUID is statistically unique.
Instant
Generate up to 100 UUIDs in a single click. No waiting, no signup, no limits.
How it works
Three steps, no hassle
Choose how many UUIDs you need
Select whether you want to generate one or multiple UUIDs at once — up to 100 in a single click.
Generate
Click 'Generate'. Each UUID is created using crypto.getRandomValues() to guarantee true uniqueness.
Copy and use
Copy a single UUID or all of them at once. Ready to paste into your code, database, or API.
FAQ
Got questions?
UUID v4 (Universally Unique Identifier, version 4) is a randomly generated 128-bit identifier. It follows the standard format of 32 hexadecimal characters grouped by hyphens: 8-4-4-4-12. The 'v4' indicates that 122 bits of data are completely random (the remaining 6 bits are fixed to identify the version and variant per RFC 4122).
In theory yes, in practice it is impossible. The probability of generating two identical UUID v4s is 1 in 5.3 × 10³⁶. To have a 50% chance of a collision you would need to generate 2.7 × 10¹⁸ UUIDs. At one billion UUIDs per second, that would take 85 years. In real systems, UUID collision is an event you do not plan for because it does not happen.
They are the same concept with different names. UUID (Universally Unique Identifier) is the term from RFC 4122. GUID (Globally Unique Identifier) is Microsoft's terminology used in .NET and COM platforms. Technically they are interchangeable: both are 128-bit identifiers. The difference is purely nomenclature by technology ecosystem.
UUIDs are preferable when you need to generate IDs across multiple systems without central coordination (microservices, offline-first apps, distributed database synchronization). Auto-increment IDs are predictable and expose data volume. UUIDs are opaque and secure by default. The trade-off is that they take more storage space and are slower in database indexes.
A UUID always follows the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where x is a hexadecimal digit (0-9, a-f), '4' indicates version 4, and 'y' is one of 8, 9, a, or b (indicates the variant). That is 32 hexadecimal digits plus 4 hyphens = 36 characters total. Example: 550e8400-e29b-41d4-a716-446655440000.
UUID v4: what they are, how they work, and when to use them
A UUID (Universally Unique Identifier) is a 128-bit identifier designed to be unique across time and space without requiring a central coordinating authority. The standard is defined in RFC 4122 and there are five versions. The most widely used in modern development is UUID v4, which generates all 122 data bits completely randomly using a CSPRNG.
UUIDs are fundamental in modern software architectures. In databases, they allow creating records with unique IDs from the client before sending them to the server, simplifying synchronization logic in offline-first apps and PWAs. In microservices, they eliminate the need for a centralized ID generation service. In REST APIs, UUIDs as resource identifiers prevent resource enumeration — an attacker cannot guess what other IDs exist.
The canonical representation of a UUID is a 36-character string: 32 lowercase hexadecimal digits separated by 4 hyphens at positions 8, 13, 18, and 23. Some systems store them without hyphens (32 characters) or as a 16-byte binary number for efficiency. Convertir.ai uses crypto.randomUUID() when available (Chrome 92+, Firefox 95+) and crypto.getRandomValues() as a fallback, ensuring compatibility and cryptographic randomness across all modern browsers.