Introduction to Sinatra: Building Web Apps with Ruby


Sinatra is a lightweight and flexible web framework for building web applications in Ruby. It's an excellent choice for small to medium-sized projects, APIs, and microservices. In this guide, we'll introduce you to the world of Sinatra and provide sample code to help you get started building web apps.


Before diving into web app development with Sinatra, make sure you have the following prerequisites:

  • Ruby installed on your system
  • A code editor (e.g., Visual Studio Code, Sublime Text)
  • Basic knowledge of Ruby programming
  • Desire and creativity to build web applications

Step 1: Installing Sinatra

Start by installing the Sinatra gem using RubyGems:

gem install sinatra

Step 2: Creating a Simple Web App

Let's create a basic Sinatra web app that responds to a GET request with "Hello, Sinatra!" The following code defines a simple app:

require 'sinatra'
get '/' do
'Hello, Sinatra!'

Save this code in a file (e.g., app.rb) and run it using the following command:

ruby app.rb

Visit http://localhost:4567 in your web browser, and you'll see "Hello, Sinatra!" displayed.

Step 3: Building Routes and Templates

Sinatra allows you to define routes and render templates. Here's an example of defining a route and rendering an HTML template:

get '/about' do
erb :about

Create an about.erb file with the HTML content you want to display in the template.


Sinatra provides a simple and elegant way to build web applications with Ruby. Whether you're creating a small website, a RESTful API, or a microservice, Sinatra's minimalist approach allows you to focus on your application's logic without the overhead of a heavyweight framework.

As you continue your journey with Sinatra, explore more advanced features like database integration, user authentication, and building RESTful APIs. Sinatra's flexibility and active community make it a valuable tool for web app development in Ruby.

Happy coding with Sinatra!