Privacy
In short
- We don't ask for an account, an email address or personal data.
- Your list, alerts and preferences stay in your Chrome.
- We don't sell or share your browsing with anyone.
- Shops receive tandem's searches from your browser, as visits of your own.
What tandem reads
Only the product pages of the supported shops you've switched on. From those pages it takes the product's name, code and price, to find it in the other shops. On other sites tandem isn't active and reads nothing.
How it gathers prices
Requests to the shops leave from your browser, with your IP address, as if you were visiting those shops yourself. To most shops tandem sends none of your cookies. The exception is the shops behind an anti-bot check: there the requests carry your cookies, because that is the only way past the check, and when a shop doesn't answer even then, tandem briefly opens one of its pages in a background tab, with your cookies and the shop's own scripts, which closes on its own as soon as the price is read. On a shop that remembers the delivery country in its session, tandem sets the country you chose in the settings, as if you had picked it from the shop's menu: that also applies to your own session on that shop, until you change it back.
When requests are sent
When you search from the results page, from the moment you click into the search box: tandem then checks the front page of the shops behind an anti-bot check, so the first search is faster. And on its own when you open a product page in a supported shop: tandem looks the same product up in the other shops you've switched on, without you asking. Those shops receive the search from your browser, with your IP address, as if you had made it yourself; where you're signed in to an account and the shop receives your cookies, it may show up among your account's searches or recently viewed products. Alerts check prices again every six hours, as long as Chrome is open, even while you're not using it. You can switch off any shop in the settings and hide tandem on a single shop from its card's menu.
Where your data stays
Your list, alerts and thresholds are saved in Chrome's storage, on this computer: they don't move to your other ones (up to version 0.4.0 they followed your account like the settings). Settings, such as the active shops, follow your account if Chrome sync is on, as bookmarks do. If you uninstall tandem, they're all deleted with it.
Permissions requested
- Storage
- Save your list, alerts and preferences in your Chrome.
- Shop sites
- Read the product's name and price and look for it in the other supported shops, and only there.
- Tabs and scripts
- Open a shop's page in the background when needed, read its price and close it right away.
- Offscreen document
- Read the shops' pages without showing them and, if you turn on title matching, download the model and compare the titles.
- Network rules
- Send the shops the headers of an ordinary visit, on tandem's own requests only.
- Notifications and timers
- Check your alerts' prices every so often and let you know when one reaches the threshold you chose.
Title matching (beta)
If you turn it on in the settings, under "Title matching", tandem downloads a model of about 41 MB from models.tandemcompare.com, our site hosted by Cloudflare: when you turn it on, again when an update of tandem brings a new model, and again if a download is interrupted or fails. As with any download, the server sees your IP address and your browser. The matching happens on your computer: for it, tandem sends no title, search or product to our site or anywhere else. The model, the offers' titles it compared and what it computes from them stay in Chrome's storage on this computer and are deleted when you turn it off. It is off until you turn it on; if you use Chrome sync, the choice follows your account to your other computers, and each one downloads the model for itself.
Anonymous statistics
The extension sends usage counts with no identifier, to understand what's really useful: the shop and country of a comparison, how many shops answered, whether there was a lower price, which shop you click and how much you save, in ranges, and the kind of filter you turn on, never the value picked. It never sends what you search for, product titles and addresses, exact prices, your list or your alerts. They go to Umami, a cookie-free statistics service with servers in the European Union. Turn them off in the settings, under "Anonymous statistics".
What we don't do
We don't use tracking cookies, we don't build profiles, we don't put ads on the shops' pages and we don't change their prices or baskets. This site uses no cookies and no statistics.
Contact
For any question write to [email protected]. If this policy changes, we update the date at the top of the page.