Open source web frameworks to accelerate development

Introduction

Open source web frameworks have exploded in popularity over the last decade, becoming essential tools for rapidly building modern web applications. By providing reusable code for common tasks like routing, request handling, and view rendering, frameworks can dramatically accelerate development compared to working from scratch with a general purpose programming language.

This article provides a comprehensive overview of some of the most widely-used open source web frameworks optimized for fast and lightweight development. We'll cover a range of options from full-stack frameworks to focused libraries for specific tasks. The goal is to highlight the key capabilities, strengths and limitations of each framework to help developers confidently select the right open source solution for their needs.

When evaluating frameworks, we'll focus on key criteria like performance, flexibility, learning curve and ecosystem support. There is often a preference for unopinionated libraries that leave many architectural decisions up to the developer vs more rigid and prescriptive frameworks. We'll emphasize frameworks well-suited for rapid prototyping and small to medium sized web apps, rather than larger complex systems.

Defining Web Frameworks

Web frameworks provide structure, conventions, and reusable code to streamline web development in a specific language like JavaScript or Python. They handle common tasks like URL routing, interacting with databases, managing sessions, rendering templates, and receiving/responding to HTTP requests so developers don't have to rewrite these features from scratch.

Key components of web frameworks include a router defining application routes, middleware for processing requests before handling them, a templating engine for rendering views to be sent to the client, and libraries for common tasks like authentication and database access. The framework connects all these components together into an integrated package.

Compared to using a general programming language by itself, frameworks reduce boilerplate code and provide tested solutions for web development challenges out of the box. This allows developers to focus on the unique aspects of their application rather than reimplementing core backend functionality.

Key benefits of using web frameworks include faster initial development, better project structure, easier maintenance as the app grows, and reduced bugs from using well-tested framework code. The tradeoff is some constraints on architecture and conventions imposed by the framework.

Criteria for Evaluation

When surveying the landscape of JavaScript web frameworks, some key factors to consider include:

• Performance - The framework should enable fast app development and efficient runtime performance. Optimizations like code splitting are highly valued.

• Flexibility - The ability to structure apps according to the developer's preferences is ideal. Less opinionated frameworks offer more architectural freedom.

• Learning curve - The framework should be relatively easy for a web developer to pick up quickly. Less complexity lowers the barrier to entry.

• Ecosystem - Having an active community providing libraries, tutorials, and support will make development much smoother.

• Lightweight - For many use cases, a minimal lightweight framework is preferable over a larger, more complex one.

• Unopinionated - Frameworks allowing developers to choose preferred libraries for tasks like templates are often ideal.

• Rapid prototyping - The ability to build and iterate on apps quickly with minimal setup and configuration time is highly valued.

• Tooling - Built-in capabilities like hot reloading can dramatically accelerate building an application.

Our framework analysis focuses on options well-suited for rapid prototyping and small to medium complexity web apps. We'll cover a spectrum from full-stack frameworks to specialized libraries for individual tasks.

Lightweight Full-stack Frameworks

Full-stack web frameworks provide an integrated set of tools for end-to-end web application development. This includes handling routing, middleware, view rendering, interfaces to databases and more right out of the box. They impose a conventional MVC-style structure on apps with pre-determined conventions and configurations.

While this can accelerate creating standard database-backed web apps, it also locks the developer into certain architectural decisions. There is a tradeoff of rapid development vs inherent flexibility to structure apps in non-standard ways.

However, many popular full-stack frameworks aim to find a middle ground by promoting convention over configuration while allowing developers to override defaults. We'll highlight frameworks optimized for lightweight, realtime applications which balance ease of use with developer freedom.

Express

Express has become the standard server framework for Node.js. It provides a minimal interface for quickly defining routes, middleware, templates and other core web application components.

Express embraces convention over configuration with a basic MVC structure out of the box. It aims to be unopinionated and flexible, allowing developers to plug in additional libraries as needed. The large ecosystem of middleware and add-ons for Express enables extending its functionality.

Key strengths of Express include its simplicity, lightweight footprint, performance and scalability. It enables some of the fastest Node.js web application development while leaving many architectural decisions like the template engine up to the developer.

Popular companies like IBM, SAP, and Symantec use Express to build fast and scalable web apps. Below is a simple example of an Express application:

const express = require('express')
const app = express()

app.get('/', (req, res) => {
  res.send('Hello World') 
})

app.listen(3000)

Fastify

Fastify is a newer Node.js web framework focusing on providing the fastest server performance possible. It uses various speed optimizations like a schema-based routing system.

Compared to Express, Fastify enforces some conventions like opt-in middleware and standardized plugin APIs to achieve better performance. However it still aims for flexibility and extensibility where possible.

Key advantages of Fastify include speed, simple scalability, TypeScript support, and an ecosystem of plugins. It strikes a balance between speed and developer experience with a moderately low learning curve. Companies like LeetCode and Klaviyo use Fastify to build high-traffic web apps efficiently. Below are benchmark tests showing Fastify outperforming Express and Hapi:

[Fastify vs Express Benchmark]

Sails.js

Sails.js is a MVC framework inspired by Ruby on Rails and built on Node.js. It aims to emulate the Rails development experience with convention over configuration, default generated code, and integrated ORM.

Out of the box, Sails includes a CLI tool for generating boilerplate code, WebSockets support, and auto-refresh on file changes. The integrated Waterline ORM provides simplified database access with support for Postgres, MySQL, MongoDB and more.

Compared to lighter frameworks like Express, Sails has a steeper learning curve due to its conventions and magic behind the scenes. But it enables very rapid database application development. Below is an example of generating an API with Sails:

# Create new Sails app
sails new testProject 

# Generate API from model
sails generate api user

This will scaffold out a full CRUD API for the User model automatically. Companies like Thumbtack use Sails to build data-driven apps quickly.

NestJS

NestJS is a robust full-stack framework for building enterprise Node.js applications. It uses strong typing with TypeScript and takes cues from Angular with its module architecture.

NestJS provides an advanced dependency injection system for assembling various modules and components. It also has outstanding support for unit and integration testing built-in.

Compared to Express or Fastify, NestJS has a significantly steeper learning curve given its complexity. But it enables scalable, testable apps with a well-defined architecture out of the box. Below is an example using NestJS modules, controllers, providers and decorators:

@Module({
  imports: [UsersModule],
  controllers: [AppController],
  providers: [AppService],  
})
export class AppModule {}

@Controller()  
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get()
  getData() {
    return this.appService.getData(); 
  }
}

NestJS enforces architecture using Angular-style decorators for routes, dependencies, etc. This provides structure at the cost of flexibility. Companies like Home24 and Sorare use NestJS to build complex enterprise apps.

Microframeworks and Routers

Microframeworks take a minimalist approach by providing only core web application functionality like routing, while leaving other components like view rendering to the developer or third-party libraries. The aim is a lightweight footprint close to the metal of the Node.js core API.

Benefits of this approach include speed, flexibility and control. The developer is responsible for assembling various components together, allowing them to pick the best libraries for tasks like templates and databases. No conventions are forced upon the application structure.

The downside is microframeworks require more legwork from the developer. Their simplicity also means lacking some of the more advanced capabilities and tooling of fuller-stack frameworks. Let's look at some popular options in this category:

Express Router

The router module from Express can be used independently to handle application routes. It provides routing capabilities with middleware and organization via route groups, but leaves other functions like views to the developer.

This allows mixing the Router with non-Express frameworks for handling routes specifically. Routers also enable separating route logic into reusable modules across applications. Below is an example Express app using Router:

// routes.js
const router = express.Router() 

router.get('/', (req, res) => {
  res.send('Home page') 
})

module.exports = router

// app.js 
const app = require('fastify')()
const router = require('./routes') 

app.use(router)

Fastify

Fastify, in addition to being a full-stack framework, also qualifies as a microframework. Its goal is to provide a bare minimum framework with only essential features like routing, but allowing any other functionality like templating to be added via plugins.

It has first-class TypeScript support and a robust plugin ecosystem for extending with any needed features. The framework itself aims to be as lightweight as possible while enabling building the exact application you need through composable plugins.

// Minimal Fastify app
const fastify = require('fastify')

const app = fastify()

app.get('/', (req, reply) => {
  reply.send({hello: 'world'}) 
})

app.listen(3000)

Polka

Polka describes itself as a "micro web server so fast, it'll make you dance!". It aims to recreate the minimal Express-style routing API but with better performance thanks to its smaller footprint.

Polka provides routing capabilities with middleware support. It uses promises rather than callbacks for async code. All other functionality like template rendering is left to the user or other libraries.

The extreme lightweight nature of Polka makes it fast and simple but lacking more advanced features. It advertises itself as "Less than 1kb" to underscore its minimalism:

const polka = require('polka');

const app = polka()
  .use(/* ... */) 
  .get('/', (req, res) => {
    // response handling  
  })
  .listen(3000);

Total.js

Total.js is a full-stack framework for Node.js, but encapsulated in a modular architecture. The framework comes with its own embedded ORM, flow engine, MVC structure, and front-end tools.

The aim is to provide a complete end-to-end framework while allowing developers to swap out any part of the system as needed. For example, you can replace the default templating engine with different view rendering options.

The downside is a smaller plugin and extension ecosystem compared to Express or Fastify. But Total.js provides a fast, opinionated framework with the flexibility to override opinions:

// Controller
exports.index = function() {
  this.view('index'); 
}

// Model  
const DB = require('total.js/database');
const db = new DB('database.json');

// View
<p>{{custom_variable}}</p> 

View Layer Libraries

Many web frameworks impose their own templating engine for view rendering. An alternative approach is to decouple the view layer entirely into separate libraries that can integrate into any framework. Some popular options include:

Pug

Pug (formerly Jade) uses whitespace and indentation rather than explicit tags to define HTML structure. It aims for clean, terse templates that are easy to read and maintain.

Pug eliminates angle brackets, closing tags and other boilerplate cruft for more concise templates. It has an active ecosystem of mixins, filters and other extensions as well. A downside is the mandatory indentation required rather than arbitrary whitespace.

// Pug template
doctype html
html
  head  
    title Pug Example
  body   
    h1 Hello World
    p This is some text

EJS

EJS stands for Effective JavaScript Templating. It uses simple JavaScript within templates for control flow like conditionals and loops. The rest of the syntax is just plain HTML for easy readability.

EJS gives the flexibility of embedded JavaScript without going fully reactive like some frameworks. It aims to provide simple templates for getting up and running quickly with vanilla Node.js.

<!-- EJS template -->
<% if (user) { %>
  <h2><%= user.name %></h2>  
<% } %>

<p>This is some static content</p>

Mustache

Mustache is a logic-less templating language supporting only variables rather than full programmatic logic in templates. It aims for minimal syntax and functionality for flexibility.

Mustache provides just template tags, variables and sections for iteration. With no built-in conditionals or helper functions, it stays simple but flexible. Developers must handle any logic in the view controller rather than the template.

<!-- Mustache template -->
<h1>{{title}}</h1>
{{#names}}
  <p>{{.}}</p>
{{/names}}

Nunjucks

Nunjucks is a JavaScript templating engine inspired by Jinja2 from Python. It provides robust functionality like template inheritance, asynchronous support, custom filters and more.

The syntax is very similar to Mustache using {{ }} tags but adds enhanced functionality like if blocks and for loops. There is also an extension ecosystem adding extras like auto-escaping variables.

Below is an example of template inheritance in Nunjucks, allowing parent templates to define reusable content blocks:

<!-- parent.njk -->
<html>
{% block head %}
  <title>Parent template</title>  
{% endblock %}

{% block content %} 
{% endblock %}
</html>

<!-- child.njk -->
{% extends "parent.njk" %}

{% block head %}
  <title>Child template</title>
{% endblock %}

{% block content %}
  <p>This is the child content</p>   
{% endblock %}

Modern Frontend Frameworks

For complex front-end UIs with dynamic data and interactivity, full frontend frameworks like React, Vue and Svelte may be preferable to simple templating languages. These provide advanced capabilities like:

• Declarative component architecture for reuse and encapsulation
• Reactive data binding and store for state management
• Virtual DOM diffing for optimized re-rendering
• Rich component ecosystem and tools

The downside is increased complexity and a steeper learning curve. Below is a brief overview of some popular options:

React

Developed by Facebook, React dominates as one of the top frontend frameworks. Core capabilities include declarative components, unidirectional data flow, and efficient re-rendering powered by a virtual DOM.

React uses JSX syntax to incorporate HTML tags within JavaScript code. The ecosystem provides routers, state management tools like Redux, and extensive UI component libraries. Many developers are already familiar with React from past experience.

// React component

const Header = () => {
  return ( 
    <header>
       <h1>Hello World</h1>
    </header>
  )
}

Vue

An up and coming alternative to React is Vue, known for approachability and ease of learning. The core library focuses on the view layer only, with other capabilities like routing and state management handled by companion libraries.

Vue provides gradual integration, allowing you to sprinkle it into existing apps before adopting it more fully. The documentation and features have made it popular for quickly building modern UIs.

<!-- Vue single file component -->

<template>
  <h1>Hello World</h1> 
</template>

<script>
export default {
  // component code...   
}
</script>

<style scoped>
/* styles */
</style>

Svelte

Svelte represents a different approach from traditional frameworks, compiling components into ideal vanilla JavaScript output rather than interpreting code at runtime. This results in better performance.

During compilation, Svelte removes any abstractions like the virtual DOM, stripping away everything not needed to render the component in the browser. The syntax is declarative and reactive, similar to Vue templates.

<!-- Svelte component -->

<script>
  let name = 'world'; 
</script>

<h1>Hello {name}!</h1> 

In situations where a full frontend framework is needed, React's maturity often makes it the safest choice while Vue and Svelte are great for faster, lighter UIs.

Specialized Libraries

For tackling specific