AtSepete Chrome extension
A free Chrome extension that shows cheaper sellers of the product you're viewing across 14 Turkish marketplaces, plus live deals.
Problem
The same product can sell at quite different prices across Turkish marketplaces, but seeing that means searching for it on five or six sites one by one. Most people don't bother and buy wherever they looked first.
The extension's old back end couldn't do the job reliably either: it depended on heavy processes running on servers and dozens of chained scheduled tasks. When I measured it, only about one visit in eight ended with a result, and at one point the system produced no results for four days without logging a single error.
Solution
I rebuilt the extension and its back end. The extension sends only the address of product pages on supported marketplaces, and the comparison happens on the server: a Next.js back end on Vercel queues the work, Python workers find other sellers of the same product, and when the result is ready the extension shows it in the corner of whatever tab you're on. A seller that looks suspiciously cheap is read a second time from a different server before it is shown.
Every part of the system writes a heartbeat; if a server goes quiet, or visits keep arriving while no results come out, an alarm goes to Telegram. The package is built and tested in GitHub Actions, and the new version has been live on the Chrome Web Store since 12 October 2026.
Key features
- Cheaper sellers: open a product page and the other sellers of the same product are listed cheapest first, with the price difference in percent.
- Live deals: big discounts from the marketplaces arrive filtered by the marketplaces, categories, minimum discount and hours you choose.
- Price alert: pick a discount level from the button next to the price on a product page, and you are told when the price drops that far.
- Pop-ups follow your rules: mute them or exclude sites, and they wait while the computer is idle, Chrome is full screen or a video call is open.
- Privacy filter: addresses of cart, checkout, order, account, login and search pages are never sent, and no name or email is ever asked for.
- The feedback form in Settings accepts screenshots, and the interface comes in light, dark and system themes.
Tech stack
In numbers
Screenshots
