Master new skills with our 21-day learning paths, broken into easy 5-minute daily lessons.

Start your journey for free.

web Intermediate 21 lessons

Browser Extension Dev

Build powerful plugins for Chrome and Firefox. Master Manifest v3, content scripts, popup UIs, and persistent background service workers.

Browser extensions can modify web pages, block ads, and automate workflows. This course covers the modern Manifest V3 standard required by the Chrome Web Store. You will learn to inject Content Scripts to manipulate the DOM of visited pages, use Service Workers for background tasks, and design Popup UIs using standard HTML/CSS. We also cover the Storage API for saving user settings and cross-browser compatibility to deploy on Firefox and Edge simultaneously.

✅ 100% Free & Lifetime Access
⏱️ 5-Minute Lessons (Bite-sized learning)
🚀 21-Lesson Path (Independent modules)
📱 Mobile Friendly (Learn anywhere)
Extension Devs
Start Learning
Secure Enrollment via SSL

Complete Course Syllabus

  • 1
    Manifest V3
    Structure, permissions, and security requirements.
  • 2
    Content Scripts
    Reading and changing the content of websites.
  • 3
    Popup & Options
    Creating UI for user interaction and settings.
  • 4
    Background Workers
    Handling events when the popup is closed.
  • 5
    Publishing
    Packaging, signing, and store submission process.

Estimated completion time: 21 lessons • Self-paced learning • Lifetime access

Career Outlook

Estimated Salary
$90k - $130k

Career Paths

Extension Developer $90k-$130k
Tools Engineer $100k-$145k
Freelance Developer $60k-$120k

What You Will Learn

Build cross-browser extensions using Manifest V3 standards
Inject Content Scripts to manipulate DOM on any website
Manage persistent state using the Extension Storage API
Handle background events with Service Workers
Publish extensions to Chrome Web Store and Mozilla Add-ons

Skills You Will Gain

JavaScript Manifest V3 DOM Manipulation Service Workers Web APIs

Who Is This For

JavaScript Developers
Tool Builders
Indie Hackers

Prerequisites

Intermediate JavaScript
DOM API Knowledge

Browser Extension Dev FAQs

Store fees?

Chrome is $5 one-time; Firefox is free.

Works on Safari?

Yes, but requires a conversion step (Xcode).

Security?

Extensions are sandboxed; we teach permission best practices.

Profitable?

Yes, many extensions are SaaS businesses.

Need more info?
All Reork courses are 100% free, self-paced, and fully accessible on mobile devices. No prior experience is required. Read our full Platform FAQ.

Tech Stack & Tools

Chrome
Firefox Developer Ed
VS Code
Web Store
Postman

Recommended Next Steps

Storybook for Components

web Intermediate

Professionalize your UI workflow. Build, test, and document components in isolation using Storybook to create robust design systems and shared libraries.

CSS Grid & Flexbox Deep Dive

web Beginner

Conquer modern CSS layouts. Master two-dimensional Grid systems and one-dimensional Flexbox alignment to build complex, responsive web interfaces without frameworks.

Full Stack Principles

web Advanced

Master the complete development lifecycle by architecting RESTful APIs, designing normalized database schemas, and building reactive frontends using the modern JavaScript stack.

Start Learning