[][src]Crate uuid

Generate and parse UUIDs.

Provides support for Universally Unique Identifiers (UUIDs). A UUID is a unique 128-bit number, stored as 16 octets. UUIDs are used to assign unique identifiers to entities without requiring a central allocating authority.

They are particularly useful in distributed systems, though can be used in disparate areas, such as databases and network protocols. Typically a UUID is displayed in a readable string form as a sequence of hexadecimal digits, separated into groups by hyphens.

The uniqueness property is not strictly guaranteed, however for all practical purposes, it can be assumed that an unintentional collision would be extremely unlikely.


By default, this crate depends on nothing but std and cannot generate UUIDs. You need to enable the following Cargo features to enable various pieces of functionality:

  • v1 - adds the Uuid::new_v1 function and the ability to create a V1 using an implementation of v1::ClockSequence (usually v1::Context) and a timestamp from time::timespec.
  • v3 - adds the Uuid::new_v3 function and the ability to create a V3 UUID based on the MD5 hash of some data.
  • v4 - adds the Uuid::new_v4 function and the ability to randomly generate a UUID.
  • v5 - adds the Uuid::new_v5 function and the ability to create a V5 UUID based on the SHA1 hash of some data.
  • serde - adds the ability to serialize and deserialize a UUID using the serde crate.

For WebAssembly, enable one of the following features depending on your JavaScript interop toolchain of choice:

By default, uuid can be depended on with:

uuid = "0.8"

To activate various features, use syntax like:

uuid = { version = "0.8", features = ["serde", "v4"] }

You can disable default features with:

uuid = { version = "0.8", default-features = false }


To parse a UUID given in the simple format and print it as a urn:

use uuid::Uuid;

fn main() -> Result<(), uuid::Error> {
    let my_uuid =
    println!("{}", my_uuid.to_urn());

To create a new random (V4) UUID and print it out in hexadecimal form:

// Note that this requires the `v4` feature enabled in the uuid crate.

use uuid::Uuid;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    #[cfg(feature = "v4")] {
        let my_uuid = Uuid::new_v4()?;
        println!("{}", my_uuid);


Examples of string representations:

  • simple: 936DA01F9ABD4d9d80C702AF85C822A8
  • hyphenated: 550e8400-e29b-41d4-a716-446655440000
  • urn: urn:uuid:F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4




Adapters for various formats for UUIDs


The implementation for Version 1 UUIDs.



A builder struct for creating a UUID.


A general error that can occur when working with UUIDs.


A Universally Unique Identifier (UUID).



The reserved variants of UUIDs.


The version of the UUID, denoting the generating algorithm.

Type Definitions


A 128-bit (16 byte) buffer containing the ID.