European Consumer Organization has given us an opportunity to build price comparison & review aggregation engine for 6 countries in which they operate. The engine is a large-scale distributed crawler, which fetches products and their prices from 120+ websites (and increasing), in 6 different countries across 15 product categories. The crawler has cloud architecture where it daily invokes many cloud computing units for distributed crawling & computation to finish the task asap. We have build a proprietary product matching engine for matching products across various websites, and an algorithm for cleanly differentiating products from its accessories. Other than being a price comparison engine, users can view the price history variations for any product and product availability at various online stores.