UUID / GUID Generator & Decoder
Generate cryptographically secure random UUID v4, time-ordered UUID v7 (RFC 9562), deterministic v3/v5, and Minecraft offline player UUIDs. Decode raw formats, BigInt integer values, and NBT int-arrays instantly in your browser.
Random — recommended for most general-purpose applications
Understanding UUID Versions (RFC 4122 & RFC 9562)
A UUID (Universally Unique Identifier) is a 128-bit value. The standard specifies versions 1 through 8, each tailored for specific architectural requirements.
UUID v1
Constructed from a 60-bit timestamp counting 100-nanosecond intervals since the Gregorian calendar reform (1582), a clock sequence, and the device's 48-bit MAC address.
UUID v3 & v5
Deterministic identifiers computed by hashing a namespace UUID and an input name. v3 uses MD5, while v5 uses SHA-1. Identical inputs always yield the identical UUID.
UUID v4
Purely random UUID. 122 out of 128 bits are generated using cryptographically secure pseudorandom number generators (CSPRNG), leaving 6 bits for version and variant.
UUID v7 (RFC 9562)
The modern RFC 9562 standard (2024). Features a 48-bit millisecond Unix timestamp prefix followed by random bits, delivering superior B-Tree database locality.
UUID v6
A field-reordered variation of UUID v1 designed to store timestamp bits in big-endian order for legacy sorting systems.
UUID v8
An RFC 9562 reserved specification allowing custom or experimental vendor-specific layouts while retaining standard variant and version bits.
Minecraft Player UUID Architecture
In Minecraft Java Edition, paid accounts receive an online UUID v4 from Mojang authorization servers. In offline (LAN or non-authenticated) environments, the client and server derive a deterministic UUID v3 from 'OfflinePlayer:<Username>'. Furthermore, Minecraft version 1.16 and newer stores entity UUIDs in NBT as an array of four 32-bit signed integers: [I; int1, int2, int3, int4].
Frequently Asked Questions
What is the key advantage of UUID v7 over UUID v4? ↓
UUID v4 is entirely random, which causes severe B-Tree page fragmentation and random I/O write penalties in relational databases. UUID v7 embeds a millisecond-precision Unix timestamp in its initial 48 bits, allowing newly inserted rows to be appended sequentially.
What are the odds of a UUID v4 collision? ↓
The total number of possible UUID v4 values is 2¹²² (approx. 5.3 × 10³⁶). Even generating one billion UUIDs per second for 100 consecutive years yields an astronomically negligible collision probability.
What does the Minecraft NBT [I; ...] format represent? ↓
Beginning in Minecraft 1.16, the game serializes 128-bit UUIDs as four 32-bit signed integers in NBT files, optimizing entity lookup speeds and reducing serialization overhead.
What is the Single Integer Value in the decoder output? ↓
A UUID is fundamentally an unsigned 128-bit binary number. When interpreted as a big-endian integer, it represents a single BigInt value up to 2¹²⁸ - 1, which is often used in mathematical models and binary network protocols.
Does UUID v1 leak hardware information? ↓
Original implementations of v1 utilized the physical network card MAC address. Modern standards (and our browser implementation) use cryptographically pseudo-random node bytes with the local multicast bit asserted to guarantee anonymity.
All operations run locally in your browser.