![Build & Test](https://github.com/farcry-ts/farcry/workflows/Build%20&%20Test/badge.svg)

Usage no npm install needed!

<script type="module">
  import farcry from 'https://cdn.skypack.dev/farcry';



Build & Test

FarCry is a TypeScript library for type-safe RPC over HTTP in NodeJS. The core idea is to make a server application using FarCry the single source of truth with regards to types. Using a single specification of each method, you get:

  • compile-time type safety,
  • input validation,
  • output validation,
  • type-safe generated client code.

With FarCry, you can speed up prototyping and application development significantly. Instead of REST, with its data-centrism, complexity and ambiguity, FarCry peforms client-server communication with JSON-RPC, which is a lightweight but versatile standard. With built-in support for call batching, FarCry helps you reduce the number of HTTP requests the client needs to perform drastically.

The aim of FarCry is to be "the missing piece" — a library that doesn't bring much new to the table, but combines the work of others into a powerful, batteries-included solution. Credits go to io-ts for runtime type-safety, Express for HTTP, jayson for JSON-RPC and TypeScript for the language.


The fundamental element is the method specification. It contains the name of the method, and type information for the parameters and return value. Try violating the types, and you'll see an error in your editor immediately.

A handler combines method specifications with function bodies, and is used to form an Express-compatible middleware. Just use it in your route of choice, and you're ready to go. It's as simple as that! Top it off by generating some client code and put your methods to use immediately.



import { handler } from "farcry";
import * as t from "io-ts";

export default handler().method(
    name: "add",
    params: {
      x: t.number,
      y: t.number,
    returns: t.number,
  async function ({ x, y }) {
    return x + y;


import express from "express";
import bodyParser from "body-parser";
import rpc from "./rpc";

const app = express();
app.use("/rpc", bodyParser.json(), rpc.middleware());

Generate client code

farcry codegen --in rpc.ts --out rpc-client.ts

In your client

import { add } from "./rpc-client";

add({ x: 10, y: 20 }).then((result) => console.log(result));
With react-farcry (experimental)
import { useMethod } from "react-farcry";
import { add } from "./rpc-client";

function Sum(props: SumProps) {
  const sum = useMethod(add, { x: props.x, y: props.y });

  if (sum === undefined) {
    return <p>Loading...</p>;

  return (
      {props.x} + {props.y} = {sum}