npm install --save @types/koa
This package contains type definitions for koa (http://koajs.com).
Files were exported from https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/koa.
These definitions were written by jKey Lu, Brice Bernard, harryparkdotio, Wooram Jun, Christian Vaagland Tellnes, Piotr Kuczynski, and vnoder.