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RFC 4122 Version 4 Standard
UUID / GUID Generator (Cryptographically Secure)
Generate RFC 4122 Version 4 Universally Unique Identifiers (UUIDs) instantly. Powered by hardware-backed Web Crypto CSPRNG with bulk generation, custom formatting, and zero duplicates.
Current Primary UUID v4
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Bulk Generation & Custom Formatting
Generated List
Understanding UUID v4: Mathematics & Collision Probability
A Universally Unique Identifier (UUID)—also known in Microsoft ecosystems as a Globally Unique Identifier (GUID)—is a 128-bit label used for information in computer systems. Version 4 UUIDs rely on pseudorandom number generators to guarantee uniqueness without requiring a central registration authority.
UUID v4 Architecture (RFC 4122)
Total Length: 128 bits (16 octets / 32 hexadecimal digits)
Entropy: 122 random bits (6 bits fixed for version 4 & variant 1)
Total Possible Combinations: 2^122 ≈ 5.3 × 10^36 unique UUIDs
Collision Probability
To put the collision risk into perspective: if you generated 1 billion UUIDs every single second for 100 consecutive years, the probability of creating a single duplicate would still be only about 1 in a billion (0.0000001%).
Frequently Asked Questions
Yes. This generator uses
crypto.getRandomValues() provided by modern browser Web Crypto API, which draws entropy directly from hardware OS kernel sources.UUID is the IETF open standard (RFC 4122). GUID is Microsoft's implementation term. They have identical 128-bit binary structures and are completely interchangeable.
Privacy Commitment: Zero network transmission. 100% Client-Side browser sandboxed execution.