Complete Chrome Extension Tutorial (Manifest V3): Build & Publish a Real Extension

We fill forms every day. Signups. Checkout pages. Job applications. Contact forms. And every time, we type: Name Email Phone number Address Over and over again. So I built a Chrome extension called TypeLess to solve exactly that. This post isn’t just about the idea—I'll walk you through how it actually works under the hood, what I learned, and the technical challenges I faced. The Core Idea The concept is simple: Save your personal details once → Autofill forms anywhere with one click. No backend. No accounts. No external APIs. Everything runs locally inside the browser. But implementing that required understanding how Chrome extensions really work. Understanding Chrome Extension Architecture (Manifest V3) A Chrome extension isn’t a normal web app. It has multiple isolated environments: Popup – The UI when you click the extension icon Background Service Worker – Runs in the background and handles events Content Script – Injected into web pages Options Page – Full settings page Each env