actix-web

name	actix-web
description	Actix-web Rust web framework. Use when building Rust HTTP services, Actor framework apps, extractors, WebSocket handlers, or performance-critical API servers on Actix RT.

actix-web

High-performance Rust web framework built on the Actix actor system with zero-cost abstractions.

Core Concepts

• Actor framework: typed actors with message passing, async handlers, and supervision trees
• Routing: #[get("/users/{id}")] attribute macros or App::new().route() for modular routing
• Extractors: type-safe request data extraction via trait impls (Json, Path, Query, Form, Data)
• Actix RT: multi-threaded async runtime optimized for HTTP throughput over Tokio

Common Patterns

• Middleware: wrap_fn closures or Transform trait for logging, auth, and request modification
• Error handling: actix_web::error::Error with ResponseError trait for typed HTTP error responses
• WebSocket: web::resource("/ws").route(web::get().to(ws_handler)) with actor-backed sessions
• Testing: actix_web::test utilities with TestRequest, call_service, and read_body_json

Best Practices

• Use web::Data<T> for shared application state instead of global statics or lazy statics
• Implement Responder trait for custom response types to keep handler return types clean
• Configure worker count via HttpServer::new().workers(n) matching CPU cores for optimal throughput
• Compile with --release for production: Actix RT performance can exceed Go and Node.js equivalents

Common Code Patterns

• HttpResponse::Ok().json(response) for typed JSON serialization via serde
• web::block(move || heavy_calc()).await for blocking CPU work off the async runtime