I Built a Price Tracker That Works on ANY Website

Online shopping has one universal frustration: you never know if the price you're seeing right now is actually a good deal. Is it the lowest it's been? Will it drop next week? Should you buy now or wait?

I asked myself that question one too many times and ended up building PriceSpy — a Chrome extension that tracks product prices and alerts you when they drop.

Why Another Price Tracker?

I tried the existing tools. Most of them only work on Amazon. A few support eBay. But none of them covered all the sites I actually shop on — especially Taobao and JD.com, which are where I buy most things.

I also didn't want to create accounts, pay subscriptions, or give up my browsing data just to track a few products. So I built something that solved my own problems:

• Multi-site support — Amazon, eBay, Walmart, Taobao, JD.com, and more
• One-click tracking — click the extension icon, set your target price, done
• Automatic alerts — desktop notification when a product hits your price
• No account needed — everything runs locally in your browser
• Free forever — no premium tier, no paywall

How PriceSpy Works

It's straightforward. When you're on a product page, click the PriceSpy icon in your Chrome toolbar. The extension reads the current price and product info, and lets you set a target price.

PriceSpy then periodically checks the price in the background. When it drops to or below your target, you get a desktop notification.

That's it. No complex setup, no account creation, no data leaving your browser.

Some features:

• Price history — see how the price has changed over time
• Smart buy recommendations — know if the current price is a good deal based on historical data
• Multi-currency support — works across different regional stores
• Privacy-first — all data stays local, no tracking, no analytics

The Tech

PriceSpy is built as a Manifest V3 Chrome extension. It uses a background service worker for periodic price checks, content scripts to read product data from supported e-commerce sites, and chrome.storage for local persistence.

One of the harder parts was building reliable price extractors for each e-commerce platform. Amazon, eBay, Walmart, Taobao, and JD.com all have different page structures, and they change frequently. I've designed it to be maintainable and updateable.

Why Free?

I built this for myself. Sharing it is just a side effect. I don't need to monetize it because it solves a real problem I have, and if it helps other people too, that's a bonus.

There are no ads, no affiliate links, no data collection. Just a tool that does one thing well.

Who This Is For

PriceSpy is for you if:

• You shop online across multiple platforms (Amazon, eBay, Taobao, JD.com, etc.)
• You're patient and willing to wait for a better price
• You value privacy and don't want another service tracking your shopping habits
• You want a simple tool without accounts or subscriptions

What's Next

I'm adding support for more e-commerce sites, improving price extraction accuracy, and building better price history visualizations. User feedback will shape the roadmap.

If you use it and find a bug, or have a site you'd like supported, let me know.

Try It

Get PriceSpy on the Chrome Web Store. One click to install, no setup needed.

Open any product page on Amazon, eBay, Taobao, or JD.com, click the PriceSpy icon, set your target price, and walk away. You'll get notified when the price drops.

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PriceSpy is a free Chrome extension by Haimo. Built for privacy-conscious online shoppers.