Develop an application that fetches product data from Keepa.com based on user-set criteria (Sale rank, Used item prices, New item prices) and displays only relevant results.

**Core Features:**

1. **User Input (Web Form):**
- Input for Sale rank range.
- Input for used item price range.
- Input for new item price range.

2. **Keepa.com API Connection:**
- Connect to Keepa to retrieve product data in real-time.

3. **Data Filtering:**
- Display only the products matching the user's set criteria.

4. **Results Display:**
- List of products with their name, sale rank, and prices.
- Direct links to the Keepa product page.

5. **Error Messages:**
- Informative messages for users in case of issues or no matches.

**Tech Stack:**
- Backend: Python (Flask or Django) or Node.js (Express.js)
- Frontend: React.js or Vue.js
- Database (if needed): MySQL or MongoDB


**Milestones:**
1. Setup, API connection & web form design.
2. Data filtering & results display development.
3. Final testing & deployment.