How to generate a random UUID v4 in Elixir?

Use UUID.uuid4() for the standard format or UUID.uuid4(:hex) for a hex string without dashes. It's compliant with RFC 4122 and easy to integrate into any Elixir application.

What's the difference between UUID v3 and v5 in Elixir UUID?

UUID v3 uses MD5 hashing, while v5 uses SHA-1; both are deterministic based on a namespace and name. V5 is more secure due to SHA-1, but v3 is faster for less critical applications.

Elixir UUID or Ecto's built-in UUID type – which should I use?

Elixir UUID is a general library for generation and manipulation, while Ecto's type is for database schemas. Use Elixir UUID if you need utility functions or non-database UUIDs; for simple Ecto integrations, the built-in type might suffice but may lack features.

How to parse a UUID string and check its version?

Call UUID.info/1 for a safe {:ok, info} tuple or UUID.info!/1 to raise on error. It returns a keyword list with :version and other details like variant and format.

Can I use custom namespaces with UUID v5 in Elixir UUID?

Yes, pass any valid UUID string as a namespace to uuid5/2, in addition to standard atoms like :dns. This allows flexible deterministic UUID generation for custom domains.

Is Elixir UUID thread-safe for concurrent use?

Yes, as a pure Elixir library leveraging Erlang's concurrency model, it's safe for concurrent environments like Phoenix applications without race conditions.

uuid — Elixir UUID Generator

What is uuid?

Elixir UUID is a library for generating and working with Universally Unique Identifiers (UUIDs) in Elixir applications. It implements RFC 4122 standards, providing functions to create UUIDs versions 1, 3, 4, and 5, along with utility functions for parsing, validating, and converting between UUID formats. It solves the need for reliable, standards-compliant unique identifier generation in Elixir projects.

Target Audience

Elixir developers who need to generate unique identifiers for distributed systems, database records, or any application requiring RFC-compliant UUIDs. Particularly useful for projects using Ecto, Phoenix, or any Elixir-based backend system.

Value Proposition

Developers choose Elixir UUID because it provides a complete, RFC 4122-compliant implementation with support for all major UUID versions, multiple output formats, and helpful utility functions in an idiomatic Elixir package. It's a reliable alternative to rolling custom UUID solutions.

UUID generator and utilities for Elixir

Use Cases

Best For

Generating unique identifiers for database records in Elixir applications
Creating RFC 4122-compliant UUIDs for distributed systems
Generating deterministic UUIDs from names using v3 or v5 algorithms
Parsing and validating UUID strings from external sources
Converting UUIDs between string, binary, and different text formats
Adding unique identifiers to Phoenix channels, PubSub messages, or Ecto schemas

Not Ideal For

Projects requiring UUID v6 or v7 for modern time-ordered identifiers
Teams needing built-in, zero-config UUID types for Ecto schemas without extra dependencies
High-throughput systems where native NIF-based UUID generation is critical for performance
Applications that only need simple random strings and want to avoid library overhead

Pros & Cons

Pros

RFC 4122 Compliance

Implements all major UUID versions (v1, v3, v4, v5) strictly following the standard, ensuring interoperability and reliability for distributed systems.

Flexible Formatting Options

Supports :default, :hex, and :urn output formats via optional parameters, catering to different use cases like database storage or URN prefixes.

Utility and Metadata Extraction

Provides info/1 and info!/1 functions to extract version, variant, and other metadata from UUID strings, aiding in validation and debugging.

Namespace Support for Deterministic UUIDs

Allows generation of v3 and v5 UUIDs using standard namespaces (:dns, :url, etc.) or custom UUIDs, enabling reproducible identifiers for names.

Cons

No Newer UUID Versions

Lacks support for UUID v6 and v7, which are newer time-ordered versions not covered by RFC 4122, limiting modern use cases.

Package Name Confusion

Renamed from 'uuid' to 'elixir_uuid' due to conflicts, which can cause issues in migration or dependency management for existing projects.

Pure Elixir Performance Trade-off

Implemented entirely in Elixir without NIFs, it may have higher overhead compared to native solutions in high-throughput scenarios.

Frequently Asked Questions

What is uuid?

Target Audience

Value Proposition

Use Cases

Best For

Generating unique identifiers for database records in Elixir applications
Creating RFC 4122-compliant UUIDs for distributed systems
Generating deterministic UUIDs from names using v3 or v5 algorithms
Parsing and validating UUID strings from external sources
Converting UUIDs between string, binary, and different text formats
Adding unique identifiers to Phoenix channels, PubSub messages, or Ecto schemas

Not Ideal For

Projects requiring UUID v6 or v7 for modern time-ordered identifiers
Teams needing built-in, zero-config UUID types for Ecto schemas without extra dependencies
High-throughput systems where native NIF-based UUID generation is critical for performance
Applications that only need simple random strings and want to avoid library overhead

Pros & Cons

Pros

RFC 4122 Compliance

Implements all major UUID versions (v1, v3, v4, v5) strictly following the standard, ensuring interoperability and reliability for distributed systems.

Flexible Formatting Options

Supports :default, :hex, and :urn output formats via optional parameters, catering to different use cases like database storage or URN prefixes.

Utility and Metadata Extraction

Provides info/1 and info!/1 functions to extract version, variant, and other metadata from UUID strings, aiding in validation and debugging.

Namespace Support for Deterministic UUIDs

Allows generation of v3 and v5 UUIDs using standard namespaces (:dns, :url, etc.) or custom UUIDs, enabling reproducible identifiers for names.

Cons

No Newer UUID Versions

Lacks support for UUID v6 and v7, which are newer time-ordered versions not covered by RFC 4122, limiting modern use cases.

Package Name Confusion

Renamed from 'uuid' to 'elixir_uuid' due to conflicts, which can cause issues in migration or dependency management for existing projects.

Pure Elixir Performance Trade-off

Implemented entirely in Elixir without NIFs, it may have higher overhead compared to native solutions in high-throughput scenarios.

Frequently Asked Questions

uuid

What is uuid?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?

uuid

What is uuid?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?