Update README.md

Author: Eric-Zhang-Developer

README.md

@@ -1,36 +1,68 @@
-This is a [Next.js](https://nextjs.org) project bootstrapped with [`create-next-app`](https://nextjs.org/docs/app/api-reference/cli/create-next-app).
+# Follow Diff
 
-## Getting Started
+A privacy-first web application that allows you to see which Instagram users you follow who don't follow you back. This tool is designed with security in mind; all data processing happens directly in your browser. Your Instagram data is never uploaded to any server.
 
-First, run the development server:
+## Overview
 
-```bash
-npm run dev
-# or
-yarn dev
-# or
-pnpm dev
-# or
-bun dev
-```
+Follow Diff provides a simple and secure way to analyze your Instagram follower relationships using your official data export. By processing your `followers.json` and `following.json` files directly in the browser, this tool ensures that your data remains completely private and never leaves your computer.
 
-Open [http://localhost:3000](http://localhost:3000) with your browser to see the result.
+The core comparison logic is implemented efficiently using a Set, which provides a time complexity of O(n + m), a significant improvement over a less optimal O(n\*m) approach, ensuring a fast and responsive experience even with large datasets.
 
-You can start editing the page by modifying `app/page.tsx`. The page auto-updates as you edit the file.
+## Live Demo
 
-This project uses [`next/font`](https://nextjs.org/docs/app/building-your-application/optimizing/fonts) to automatically optimize and load [Geist](https://vercel.com/font), a new font family for Vercel.
+You can try out the application here: [https://follow-diff.vercel.app/](https://follow-diff-theta.vercel.app/)
 
-## Learn More
+## How It Works
 
-To learn more about Next.js, take a look at the following resources:
+1.  **Request Your Data**: First, you'll need to request your data from Instagram. A tutorial on how to do this is available on the application's website.
+2.  **Upload Your Files**: Once you have your `followers.json` and `following.json` files, you can drag and drop them into the application.
+3.  **See the Difference**: The application will then process the files and display a list of users who do not follow you back.
 
-- [Next.js Documentation](https://nextjs.org/docs) - learn about Next.js features and API.
-- [Learn Next.js](https://nextjs.org/learn) - an interactive Next.js tutorial.
+## Key Features
 
-You can check out [the Next.js GitHub repository](https://github.com/vercel/next.js) - your feedback and contributions are welcome!
+* **Client-Side Processing**: All file processing and data analysis happen in the browser. No user data is ever sent to a server, guaranteeing privacy.
 
-## Deploy on Vercel
+* **Efficient Comparison Algorithm**: Utilizes a JavaScript `Set` for fast and efficient comparison of follower and following lists.
 
-The easiest way to deploy your Next.js app is to use the [Vercel Platform](https://vercel.com/new?utm_medium=default-template&filter=next.js&utm_source=create-next-app&utm_campaign=create-next-app-readme) from the creators of Next.js.
+* **Robust Type-Safety**: Employs TypeScript and Zod for schema validation to ensure the data from Instagram's export files is correctly parsed and handled, preventing runtime errors and improving maintainability.
 
-Check out our [Next.js deployment documentation](https://nextjs.org/docs/app/building-your-application/deploying) for more details.
+* **Comprehensive Testing**: Includes a suite of tests using Jest and React Testing Library to ensure the reliability of core logic and UI components. The test suites achieve the following coverage:
+    * **Statements**: 94.64%
+    * **Branches**: 88.88%
+    * **Functions**: 83.33%
+    * **Lines**: 98.03%
+
+
+## Setup
+
+To run this project locally:
+
+1.  Navigate to the project directory:
+    ```bash
+    cd follow-diff
+    ```
+2.  Install dependencies:
+    ```bash
+    npm install
+    ```
+3.  Run the development server:
+    ```bash
+    npm run dev
+    ```
+
+## Tech Stack
+
+### Frontend
+
+  * **React**
+  * **Next.js**
+  * **TypeScript**
+  * **TailwindCSS**
+  * **Zod** (for schema validation)
+  * **React-Dropzone** (for file uploads)
+  * **Jest & React Testing Library** (for testing)
+  * **Vercel** (for deployment)
+
+### Backend
+
+This project is a pure frontend application and does not have a backend.