Introduction

Relic is a modern, high-performance web server framework inspired by Shelf and built by the Serverpod team to meet the demanding requirements of modern web applications. Relic provides a robust, type-safe, and efficient foundation for building scalable web services.

Why Relic?

While Shelf has been a solid foundation for Dart web applications, several areas for improvement were identified. Rather than work around these limitations, Relic was created as a next-generation framework that maintains Shelf's familiar structure while delivering significant enhancements.

Features

Relic aims to be a comprehensive web server framework for Dart. It provides a wide range of features out of the box and allows you to extend it with middleware. Here are some of the key features:

🔒 Type Safe

Strongly typed APIs with validated HTTP headers.

⚡ Fast

High performance through trie-based routing and LRU caching.

🔌 WebSockets

Built-in WebSocket support for real time communication.

🔧 Middleware

Composable middleware pipeline with router integration.

👨‍💻 Dev Ready

Great IDE support, clear errors, and full documentation.

🚀 Production

Production-ready with high test coverage (3,000+ tests).

Comparison with Shelf

Relic started out as a clone of Shelf, but has since diverged. An adapter is being built so that you can use Shelf middleware with Relic. Here is a comparison of some of the key differences:

Feature	Shelf	Relic
Type Safety	❌ Uses dynamic types	✅ Strongly typed APIs with validated HTTP headers
Routing	❌ Linear scan over routes	✅ Built-in trie-based router
WebSockets	❌ External packages	✅ Built-in support
Performance	✅ Good	✅ Optimized (trie routing, LRU cache)
Path Parameters	❌ String-based	✅ Symbol-based
Static Files	❌ Limited	✅ Includes cache busting & etag support
Control Flow	❌ Exceptions for control flow	✅ Explicit state machine
Request State	❌ Untyped context bag	✅ Context properties with IDE discoverability
Body Model	❌ Body and encoding are separate	✅ Unified