I Built a Cross-Platform Price Comparison Tool...

Retail arbitrage is conceptually simple: buy a product on one platform where it's cheap, sell it on another where it's expensive, and pocket the difference. In practice, it's death by browser tabs. You're looking at a product on Amazon Japan. Is it cheaper on Mercari? What about Yahoo Auctions? You open three more tabs, type the product name into each search bar, scroll through results, mentally calculate fees, and try to remember the original price while comparing. By the time you finish, you'v