Consumer Tool / E-Commerce
Pricewatch
A multi-store price tracking tool. Paste any product URL, track price history over time, and get instant alerts when the price drops below your target.
Overview
Pricewatch lets users track prices on any product from any online store. Paste a URL, set a target price, and get an email or push notification when the price drops. The dashboard shows price history charts so users can spot trends and buy at the right time. Works across Amazon, eBay, Walmart, Best Buy, and hundreds of other retailers.
The Problem
Online prices fluctuate constantly. The same product can cost 30% less next week, but nobody checks every day. Existing tools like CamelCamelCamel only work with Amazon. Honey focuses on coupons, not price tracking. Browser extensions are clunky and stop working when the store updates their HTML. Users want a simple tool: paste a link, set a price, get notified.
Approach
Universal product scraper
Built a scraping engine that extracts prices from any e-commerce page using a combination of structured data (JSON-LD, Open Graph), CSS selector heuristics, and a fallback headless browser for JavaScript-rendered pages. New store adapters are added through a plugin system. The scraper runs on a schedule (every 4 hours per product) and stores historical price points.
Price history and trend analysis
Every price check is logged with a timestamp. The dashboard renders interactive charts showing price history over 30, 90, or 365 days. A trend indicator shows whether the current price is above or below the average for the tracking period. Users can see if a 'sale' is actually a good deal or if the price was lower two weeks ago.
Alert system with smart thresholds
Users set a target price per product. When the scraped price drops below the target, an alert fires via email or browser push notification. Smart thresholds also detect percentage drops (any 20%+ drop triggers an alert even without a specific target). Alerts include a direct buy link and the price history chart.
Cross-store price comparison
When users track a product, Pricewatch searches for the same item on other supported stores. The comparison view shows current prices across all retailers for the same product, sorted by price. This helps users find the cheapest option without manually checking each store.
Challenges
Handling anti-scraping measures
Large retailers actively block scrapers with CAPTCHAs, rate limits, and bot detection. Built a rotation system with multiple proxy providers, randomized request timing, and realistic browser fingerprints. For stores with aggressive blocking, the headless browser approach with residential proxies achieves a 97% success rate on price extraction.
Identifying the same product across stores
The same product has different names, SKUs, and URLs on different stores. Built a matching engine that compares product titles, UPC codes (when available), brand + model combinations, and image similarity. The matching is conservative: it only suggests cross-store matches above a 90% confidence threshold, and users can confirm or reject matches.
Results
Pricewatch tracks over 50,000 products for 8,000 registered users, with an average savings of $47 per alert acted on.
8,000+
Registered users
50K
Products actively tracked
$47
Average savings per alert