mion : Full Stack APIs at the speed of light 🚀

mion is a lightweight TypeScript-based framework designed for building serverless APIs. It aims to provide a great developer experience and is optimized for serverless environments. With mion, you can quickly build APIs that are type-safe, with automatic validation and JSON round trip out of the box.

Check Out The Website And Documentation 📚

Why Another Framework?

Serverless applications have different requirements compared to conventional server apps and there are not many frameworks that offer type-safe APIs with automatic validation and JSON round trip by default.

mion addresses these challenges by offering a lightweight and opinionated framework focused on simplicity and developer experience.

Features

Status	Name	Description
✅	RPC-like Router	Provides an RPC-style router for handling API requests
✅	Automatic Validation	Automatically validates data received by the API
✅	Automatic JSON Round Trip	Data sent by the API comes back as the same values
✅	AWS Lambda Handler	Seamless integration with AWS Lambda for serverless execution
✅	HTTP Server	Includes an HTTP server module for handling API requests
✅	Automatic TypeScript Client	Fully typed client without need of compilation

Opinionated Approach (Aka: RPC Like)

mion is designed with a Remote Procedure Call (RPC) style and works exclusively with JSON data. The framework prioritizes quick development, fast startups, and minimal abstractions. It follows a convention-over-configuration approach and focuses on performance and developer experience.

Fast

We have prioritized and tracked performance during the development of the framework, we even have many discarded features and experiments when there was a performance degradation compared to previous versions. Our goal is to have similar performance to fastify which we consider the gold standard in node.js frameworks!

For full benchmarks and comparison against other frameworks please visit mion.pages.dev/benchmarks.
We know! benchmarks are just benchmarks, but if you don't keep performance in mind you end up like express 😅

They live in this repository (container/mion-bench/) and are re-run on every docs deploy against the code on main, so the published numbers never describe an older release:

• Hello World — routing and framework overhead
• Light validation — a small typed payload
• Heavy validation — a ~1 KB nested model
• Payload sizes — the same route from ~1 KB to ~4 MB

Routing

mion's router is lightweight and fast. Unlike traditional routers, it uses a Remote Procedure Call (RPC) style of routing. The Http method is not relevant, there are no parameters in the Url and data is sent and received in JSON format via the request body or headers. mion's router leverages a simple in-memory map for route lookup, making it extremely fast.

Apis are composed of routes and middleware, declared through the helpers createMionRouter returns. Routes are methods that can be called remotely from the client and have a specific url, while middleware are auxiliary methods that get executed before or after a route.

To learn more about the router, refer to the Router Documentation.

Automatic JSON Round Trip & Validation

mion utilizes RunTypes for automatic validation and JSON round trip. RunTypes enables type information to be available at runtime, allowing for automatic validation and JSON round trip of data.

By leveraging runtime types, mion offers advanced capabilities such as request validation and the request/response JSON round trip that typically involves using multiple framework and loads of code or boilerplate to be manually written by developers.

RunTypes: developed in this repo

This monorepo is also the home of RunTypes (the RunTypes/* npm packages): the compile-time runtime-type resolver built on TypeScript 7 / typescript-go that powers mion's validation and JSON round trip. It was developed for a while in a separate repository; that full history has been merged back here.

RunTypes has its own docs section: mion.pages.dev/runtypes. Its code lives under packages/run-types* and ts-go-runtypes/.

Full Stack APIs

Thats it 👆, thats all you need to write a Fully Type Safe Api and Client   🚀
All parameters and return values will also be automatically validated and make the JSON round trip without any extra code required.

Contributing

Contributors and maintainers are welcome 👍

Mion's philosophy is simplicity, so we don't want to add many features! As an small open source project we want to keep it simple and keep features to maintain at a minimum, that said contributions to mion are encouraged! Please open issues and submit pull requests for any improvements or bug fixes.

The project is organized as a monorepo using pnpm workspaces. Each package within the monorepo is compiled and tested individually using TypeScript and Vitest.

Install

This repo uses pnpm (with a security-hardened .npmrc: pinned versions, 30-day minimum release age, no install scripts, no non-registry sources). Do not run npm install.

pnpm install --frozen-lockfile

Publishing

Releases run through the repo's own release train, which bumps every package in lockstep, packs, verifies and publishes:

pnpm miondevx release --help

Powered by:

• Typescript
• @MaJerez

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License: MIT