--- /dev/null
+# on-headers
+
+[![NPM Version](https://img.shields.io/npm/v/on-headers.svg?style=flat)](https://www.npmjs.org/package/on-headers)
+[![Node.js Version](https://img.shields.io/badge/node.js->=_0.8-blue.svg?style=flat)](http://nodejs.org/download/)
+[![Build Status](https://img.shields.io/travis/jshttp/on-headers.svg?style=flat)](https://travis-ci.org/jshttp/on-headers)
+[![Coverage Status](https://img.shields.io/coveralls/jshttp/on-headers.svg?style=flat)](https://coveralls.io/r/jshttp/on-headers)
+[![Gittip](https://img.shields.io/gittip/dougwilson.svg?style=flat)](https://www.gittip.com/dougwilson/)
+
+Execute a listener when a response is about to write headers.
+
+## Install
+
+```sh
+$ npm install on-headers
+```
+
+## API
+
+```js
+var onHeaders = require('on-headers')
+```
+
+### onHeaders(res, listener)
+
+This will add the listener `listener` to fire when headers are emitted for `res`.
+The listener is passed the `response` object as it's context (`this`). Headers are
+considered to be emitted only once, right before they are sent to the client.
+
+When this is called multiple times on the same `res`, the `listener`s are fired
+in the reverse order they were added.
+
+## Examples
+
+```js
+var http = require('http')
+var onHeaders = require('on-headers')
+
+http
+.createServer(onRequest)
+.listen(3000)
+
+function addPoweredBy() {
+ // add if not set by end of request
+ if (!this.getHeader('X-Powered-By')) {
+ this.addHeader('X-Powered-By', 'Node.js')
+ }
+}
+
+function onRequest(req, res) {
+ onHeaders(res, addPoweredBy)
+
+ res.setHeader('Content-Type', 'text/plain')
+ res.end('hello!')
+}
+```
+
+## License
+
+[MIT](LICENSE)