# Kemal [](https://travis-ci.org/sdogruyol/kemal)

Lightning Fast, Super Simple web framework for Crystal. Inspired by Sinatra

Kemal is under heavy development and currently supports Crystal 0.9.0.

Super Simple <3

require "kemal"

get "/" do
  "Hello World!"
end

Build and run!

crystal build --release src/kemal_sample.cr
./kemal_sample

Go to http://localhost:3000

Check samples for more.

Super Fast <3

Numbers speak louder than words.

Framework	Request Per Second	Avg. Response Time
Kemal (Production)	64986	170μs
Sinatra (Thin)	2274	43.82ms

These results were achieved with wrk on a Macbook Pro Late 2013. (2Ghz i7 8GB Ram OS X Yosemite)

Installation

Kemal supports Crystal 0.9.0 and up. You can add Kemal to your project by adding it to shard.yml

name: your-app

dependencies:
  kemal:
    github: sdogruyol/kemal
    branch: master

Routes

In Kemal, a route is an HTTP method paired with a URL-matching pattern. Each route is associated with a block:

  get "/" do
  .. show something ..
  end

  post "/" do
  .. create something ..
  end

  put "/" do
  .. replace something ..
  end

  patch "/" do
  .. modify something ..
  end

  delete "/" do
  .. annihilate something ..
  end  

Environment

Accessing the environment (query params, body, content_type, headers, status_code) is super easy. You can use the environment returned from the block:

  # Matches /hello/kemal
  get "/hello/:name" do |env|
    name = env.params["name"]
    "Hello back to #{name}"
  end

  # Matches /resize?width=200&height=200
  get "/resize" do |env|
    width = env.params["width"]
    height = env.params["height"]
  end

  # Easily access JSON payload from the params.
  # The request content type needs to be application/json
  # The payload
  # {"name": "Serdar", "likes": ["Ruby", "Crystal"]}
  post "/json_params" do |env|
    name = env.params["name"] as String
    likes = env.params["likes"] as Array
    "#{name} likes #{likes.each.join(',')}"
  end

  # Set the content as application/json and return JSON
  get "/user.json" do |env|
    kemal = {name: "Kemal", language: "Crystal"}
    env.content_type = "application/json"
    kemal.to_json
  end

  # Add headers to your response
  get "/headers" do |env|
    env.add_header "Accept-Language", "tr"
    env.add_header "Authorization", "Token 12345"
  end

Middlewares

You can create your own middlewares by inheriting from HTTP::Handler

class CustomHandler < HTTP::Handler
  def call(request)
    puts "Doing some custom stuff here"
    call_next request
  end
end

Kemal.config.add_handler CustomHandler.new

Static Files

Kemal has built-in support for serving your static files. You need to put your static files under your /public directory.

E.g: A static file like /public/index.html will be served with the matching route /index.html.

Production / Development Mode

By default Kemal starts in developmentmode and logs to STDOUT.

You can use production mode to redirect the output to a file. By default Kemal logs the output to kemal.log.

You can start Kemal in production mode by:

./your_app -e production

Thanks

Thanks to Manas for their awesome work on Frank.