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var merry = require("merry")

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merry v5.5.2

Modular http framework


Cute streaming API framework

Merry is a little Node framework that helps you build performant applications with little effort. We don't think that "fast" and "cute" should be mutually exclusive. Out of the box we've included consistent logging, standardized error handling, a clean streams API and plenty of nuts, bolts and options to customize merry to fit your use case. We hope you have a good time using it. :v: -Team Merry


  • fast: using Node streams, merry handles request like no other
  • fun: helps with boring stuff like error handling
  • communicative: standardized ndjson logs for everything
  • sincere: doesn't monkey patch Node's built-ins
  • linear: smooth sailing from tinkering to production
  • very cute: 🌊🌊⛵️🌊🌊

Table of Content


var merry = require('merry')

var app = merry()

app.route('GET', '/', function (req, res, ctx) {'oh hey, a request here')
  ctx.send(200, { cute: 'butts' })

app.route('default', function (req, res, ctx) {'Route doesnt exist')
  ctx.send(404, { message: 'nada butts here' })

$ node index.js | merry


Merry uses the pino logger under the hood. When you create a new merry app, we enable a log forwarder that by default prints all logs to process.stdout.

There are different log levels that can be used. The possible log levels are:

  • debug: used for developer annotation only, should not be enable in production
  • info: used for transactional messages
  • warn: used for expected errors
  • error: used for unexpected errors
  • fatal: used for critical errors that should terminate the process
var merry = require('merry')
var app = merry()

app.route('GET', '/', function (req, res, ctx) {
  ctx.log.debug('it works!')'hey')
  ctx.log.error('oh no!')
  ctx.log.fatal('send help')

The difference between an expected and unexpected error is that the first is generally caused by a user (e.g. wrong password) and the system knows how to respond, and the latter is caused by the system (e.g. there's no database) and the system doesn't know how to handle it.

Error handling

Error handling is different for each application. Errors come in different shapes, have different status codes, so we can't provide a one-size-fits-all solution. But we do think that having consistent error messages is useful, so Merry comes with a recommended pattern to handle errors.

// errors.js
exports.ENOTFOUND = function (req, res, ctx) {
  ctx.send(404, {
    type: 'invalid_request_error',
    message: 'Invalid request data'

exports.EDBOFFLINE  = function (req, res, ctx) {
  ctx.send(500, {
    type: 'api_error',
    message: 'Internal server error'
// index.js
var errors = require('./errors')
var merry = require('merry')
var db = require('my-cool-db')

var app = merry()

app.route('GET', '/', function (req, res, ctx) {
  db.get('some-key-from-request', function (err, data) {
    if (err) return errors.ENOTFOUND(req, res, ctx)
    ctx.send(200, data)



Generally there are two ways of passing configuration into an application. Through files and through command line arguments. In practice it turns out passing environment variables can be done with less friction than using files. Especially in siloed environments such as Docker and Kubernetes where mounting volumes can at times be tricky, but passing environment variables is trivial.

Merry ships with an environment argument validator that checks the type of argument passed in, and optionally falls back to a default if no value is passed in. To set the (very common) $PORT variable to default to 8080 do:

var merry = require('merry')
var env = { PORT: 8080 }
var app = merry({ env: env })

And then from the CLI do:

node ./server.js
// => port: 8080

PORT=1234 node ./server.js
// => port: 1234


Merry uses server-router under the hood to create its routes. Routes are created using recursive arrays that are turned into an efficient trie structure under the hood. You don't need to worry about any of this though; all you need to know is that we've tested it and it's probably among the fastest methods out there. Routes look like this:

var merry = require('merry')
var app = merry()
app.route('GET', '/', handleIndex)
app.route('PUT', '/foo', handleFoo)
app.route('GET', '/foo/:bar', handleFoobarPartial)

Partial routes can be set using the ':' delimiter. Any route that's registered in this was will be passed to the ctx argument as a key. So given a route of /foo/:bar and we call it with /foo/hello, it will show up in ctx as { bar: 'hello' }.


We do provide you with a way to access your route's ctx via app.use

var merry = require('merry')
var app = merry()
app.use(function (req, res, ctx) { = 'bar'


For http2 support you will need to provide a key and a cert to establish a secure connection. These can be passed as part of merry's opts. If http2 is not available, an error will be thrown to upgrade your node version to > v8.4.0.

var merry = require('merry')
var fs = require('fs')

var opts = {
  key: fs.readFileSync('server-key.pem'),
  cert: fs.readFileSync('server-cert.pem')
var app = merry(opts)



app = merry(opts)

Create a new instance of merry. Takes optional opts:

  • opts.logLevel: defaults to 'info'. Determine the cutoff point for logging
  • opts.logStream: defaults to process.stdout. Set the output writable stream to write logs to
  • opts.env: pass an object containing env var assertions
  • opts.key: key to create an http2 connection
  • opts.cert: cert to create an http2 connection

app.use(req, res, ctx)

Allows you to modify req, res and ctx objects prior to handling a route.

app.route(method|methods, route, handler)

Register a new handler for a route and HTTP method. Method can be either a single HTTP method, or an array of HTTP methods.

app.route('default', handler)

Register a new default handler that will be called if no other handlers match.


Each route has a signature of (req, res, ctx):

  • req: the server's unmodified req object
  • res: the server's unmodified res object
  • ctx: an object that can contain values and methods


Parameters picked up from the router using the :route syntax in the route.


Environment variables passed into the choo({ env }) constructor.


Log data. Loglevel can be one of trace, debug, info, warn, error, fatal. Can be passed varying arguments.

ctx.send(statusCode, data, [headers])

Efficiently encode JSON, set the appropriate headers and end the request. Uses streams under the hood.

ctx.parse(jsonStream, callback(err, data))

Parse a stream of JSON into an object. Useful to decode a server's req stream with.

handler = app.start()

Create a handler that can be passed directly into an http server.

var merry = require('merry')
var http = require('http')

var app = merry()
app.route('GET', '/', handleRoute)

var handler = app.start()
var server = http.createServer(handler)

function handleRoute (req, res, ctx, done) {
  done(null, 'hello planet')


Start the application directly and listen on a port:

var merry = require('merry')

var app = merry()
app.route('GET', '/', handleRoute)

function handleRoute (req, res, ctx, done) {
  done(null, 'hello planet')


$ npm install merry

See Also




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