Crate uuid [] [src]

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 [Uuid]s. 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 a UUIDV1Context 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.

By default, uuid can be depended on with:

uuid = "0.6.0-beta"

To activate various features, use syntax like:

uuid = { version = "0.6.0-beta", features = ["serde", "v4"] }

You can disable default features with:

uuid = { version = "0.6.0-beta", default-features = false }


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

use uuid::Uuid;

fn main() {
    let my_uuid = Uuid::parse_str("936DA01F9ABD4d9d80C702AF85C822A8").unwrap();
    println!("{}", my_uuid.urn());

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

Be careful when using this code, it's not being tested!
// Note that this requires the `v4` feature enabled in the uuid crate.

use uuid::Uuid;

fn main() {
    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




An adaptor for formatting a Uuid as a hyphenated string.


An adaptor for formatting a Uuid as a simple string.


An adaptor for formatting a Uuid as a URN string.


A Universally Unique Identifier (UUID).


A stateful context for the v1 generator to help ensure process-wide uniqueness



Error details for string parsing failures.


The reserved variants of UUIDs.


The version of the UUID, denoting the generating algorithm.



A UUID of the namespace of fully-qualified domain names


A UUID of the namespace of ISO OIDs


A UUID of the namespace of URLs


A UUID of the namespace of X.500 DNs (in DER or a text output format)

Type Definitions


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