docs

Azu Web Framework

Azu is a high-performance web framework for Crystal emphasizing type safety, modularity, and real-time capabilities.

Quick Example

require "azu"

module MyApp
  include Azu

  configure do
    port = 3000
  end
end

struct HelloRequest
  include Azu::Request
  getter name : String = "World"
end

struct HelloResponse
  include Azu::Response
  def initialize(@name : String); end
  def render
    "Hello, #{@name}!"
  end
end

struct HelloEndpoint
  include Azu::Endpoint(HelloRequest, HelloResponse)
  get "/"
  def call : HelloResponse
    HelloResponse.new(hello_request.name)
  end
end

MyApp.start [
  Azu::Handler::Logger.new,
  Azu::Handler::Rescuer.new
]

Architecture

HTTP Request → Router → Middleware Chain → Endpoint → Response
                                              ↓
                                    Request Contract (validation)

Endpoints are type-safe handlers with:

• Request Contract: Validates and types incoming data
• Response Object: Handles content rendering
• Middleware: Cross-cutting concerns (auth, logging, etc.)

Core Features

Feature	Description
Type-Safe Contracts	Compile-time validation via Azu::Request
Radix Routing	O(log n) lookup with path caching
WebSocket Channels	Real-time bidirectional communication
Live Components	Server-rendered with client sync (Spark)
Multi-Store Cache	Memory and Redis with auto-metrics
Middleware Stack	CORS, CSRF, Rate Limiting, Logging

Documentation

New to Azu?	Need to do something?	Looking for API?	Want to understand?
Tutorials	How-To Guides	Reference	Explanation

Tutorials

Step-by-step lessons to learn Azu:

• Getting Started - Install and create your first app
• Building a User API - Complete CRUD API tutorial
• Adding WebSockets - Real-time features
• Working with Databases - CQL integration
• Testing Your App - Write comprehensive tests
• Deploying to Production - Production deployment

How-To Guides

Task-oriented guides for specific goals:

• Endpoints - Create endpoints, handle parameters, return formats
• Validation - Validate requests and models
• Real-Time - WebSocket channels and live components
• Database - Schema, models, queries, transactions
• Caching - Memory and Redis caching
• Middleware - Custom handlers and logging
• Deployment - Production, Docker, scaling
• Performance - Optimize endpoints and queries

Reference

Technical specifications and API documentation:

• Core API - Endpoint, Request, Response, Channel, Component
• Handlers - Built-in middleware handlers
• Configuration - All configuration options
• Database - CQL API, validations, query methods
• Error Types - HTTP error classes

Explanation

Conceptual understanding of Azu:

• Architecture - How Azu works
• Request Lifecycle - Request flow
• Type Safety - Compile-time guarantees
• Design Decisions - Why Azu is built this way

Resources

• FAQ - Common questions and troubleshooting
• Contributing - Development setup and guidelines