Privacy policy
Last updated: November 4, 2026
Tagtwin is a free Chrome extension that checks whether a store is showing you a higher price than other shoppers see for the same product, and warns you on the page when it is. This policy explains, in plain language, what Tagtwin collects, what it never collects, what happens to the data, and how to delete it.
If you have a question that this page doesn't answer, email hello@tagtwin.com.
Nothing happens until you choose
When you install Tagtwin, it opens a page that explains what it collects. It does nothing at all (no reading pages, no checks, no sending) until you click one of two buttons:
- Share & start (full sharing), or
- Local only & start.
Nothing is pre-selected. You can switch between the two at any time in Tagtwin's Settings.
How Tagtwin checks a price
When you open a product page on a shopping site, Tagtwin reads the price the page shows you. It then loads the same product page a few more times in the background, as "strangers": hidden copies with no cookies, no saved logins and no browsing history, one looking like a desktop computer, one like a phone, and one arriving from a Google search. It reads the price each stranger is shown and compares.
- The strangers never use your account, your cookies or your cart. Your real session is never touched.
- The strangers never click, add to cart, log in or buy anything.
- These extra page loads go to the store from your own internet connection, just like a normal visit, so the store sees a few extra visits to that product page.
- Each product is checked at most once every 6 hours.
What Tagtwin collects
Tagtwin only reads product pages on shopping sites. It does not collect anything from other websites.
With full sharing, Tagtwin sends our server:
- The product and the price you were shown: the store's website (for example, ulta.com), the store's product code (or, if the page has none, the product page's address without any search or tracking parameters), the price and the currency.
- The prices the stranger checks saw for the same product.
- Whether you appeared to be logged in to the store: yes, no or unknown. Tagtwin guesses this on your computer from the store page's header (for example, whether it shows a "Sign in" link) and sends only the yes, no or unknown, never your name or account details.
- Rough region and device type. The region is broad (for example, "North America" or "Europe") and comes from the version of the store's site you're on, not from your device's location. The device type is "desktop" or "mobile".
- The hour the price was seen (rounded down to the hour, never the exact time).
- A random ID for this install. It's a random number created on your computer when you choose full sharing. It is not based on anything about you or your computer. It exists so that the wipe can find and delete everything you've sent.
With local only, Tagtwin still sends the product, the price you were shown, the hour, and the rough region and device type, but anonymously: no install ID and no stranger-check results. Nothing in it can be tied back to you, which also means it can't be found again to delete it (see "Deleting your data").
Our data format also has fields for how old your store account is and how much you've spent. Tagtwin does not read either of these today; they are always sent as "unknown".
What Tagtwin never collects
- Your name, email address, postal address or phone number
- Payment details or passwords
- Anything from websites that aren't shopping sites
- Your browsing history
- Your precise location
Sensitive stores send nothing
On pharmacies and health stores, adult sites, firearms stores and similar sensitive stores, Tagtwin sends nothing at all, in either sharing level. It recognizes them from a list of known sites and from sensitive words in the product's category, name, page trail and web address. When it isn't sure, it treats a store as sensitive and sends nothing. It may still run the check on your own computer and warn you there.
Your connection, for spam protection only
Like any website, our server sees the internet (IP) address your data comes from. We never store your IP address itself and never attach it to your data. To stop one person from flooding the system with fake prices, the server keeps a scrambled, one-way fingerprint of the address (it can't be turned back into the address). These fingerprints are deleted automatically within 7 days. Our hosting provider also keeps short-lived technical logs of requests to our server for security and troubleshooting.
What we do with the data
- Warn you. The comparison with the stranger checks happens on your computer, and the warning is shown to you on the page.
- Explain why prices differ. We study the data to work out which shopper traits and behaviors lead stores to show higher prices (for example, being logged in), so Tagtwin can tell shoppers what is raising their price and how to avoid it.
- Publish findings about stores. We may publish findings about stores and their pricing practices, for anyone to read. Findings are only ever aggregate statistics about groups of at least 20 shoppers. They never include anything that could identify a shopper, and we never publish or share individual records.
We do not:
- sell your data;
- use it for advertising, or share it with advertisers or data brokers;
- use it to decide anything about you, such as creditworthiness or lending.
Tagtwin's use of information received through Chrome will adhere to the Chrome Web Store User Data Policy, including the Limited Use requirements.
Where the data is stored
The data Tagtwin sends is stored in a database hosted by Supabase, in the United States. Only our own server can read or write it; it is not publicly accessible.
On your computer, Tagtwin keeps its settings (your sharing choice and install ID) and the results of recent checks, so it can show them in the popup and avoid re-checking the same product. These stay on your computer.
Two small things also stay on your computer. If Tagtwin asks you to rate it, your answer ("rated" or "no thanks") is kept so it never asks again; it says nothing about you, so the wipe keeps it too. And when you share a catch, the image or text is made on your computer and goes only where you paste or save it. Tagtwin doesn't send it anywhere and doesn't record that you shared.
How long we keep it
| Data | Kept for |
|---|---|
| Prices you were shown (both sharing levels) | 180 days, or until you wipe them (full sharing) |
| Stranger-check results (full sharing) | 180 days, or until you wipe them |
| Scrambled connection fingerprints | up to 7 days |
| Settings and recent results on your computer | until you wipe them or uninstall Tagtwin |
Deleting your data
In Tagtwin's Settings, Permanently wipe my data deletes everything Tagtwin has stored about you, on your computer and on our server, immediately. There is no waiting period. Tagtwin only says "Done" once our server has confirmed the deletion; if it can't reach the server, it says so and keeps retrying.
To be honest about the limits:
- The wipe finds your server data by your install ID. Prices sent in local-only mode carry no install ID, so nothing can find them, including us. They are deleted automatically after 180 days.
- If you switch from full sharing to local only, Tagtwin keeps your install ID so a later wipe still deletes what you sent while sharing. Prices sent after the switch are anonymous and aren't covered.
- The scrambled connection fingerprints carry no install ID either; they are deleted within 7 days.
- Uninstalling Tagtwin deletes what's on your computer, including the install ID, but not what's on our server. To delete your server data, wipe before you uninstall. Otherwise it is deleted automatically after 180 days.
After a wipe at full sharing, Tagtwin creates a new random install ID, so nothing sent afterwards is linked to what you deleted.
Your rights
Depending on where you live (for example, in the European Union, the United Kingdom or California), you may have the right to access, correct or delete your personal data, to object to or limit how it's used, and to withdraw your consent. Tagtwin relies on your consent, which you give on the first-run page. You can withdraw it at any time by switching to local only, wiping your data, or uninstalling the extension.
The wipe is the fastest way to delete your data. For anything else, email hello@tagtwin.com. Because Tagtwin doesn't know who you are, we can only find data that carries your install ID, and we can't find anonymous local-only data at all.
We don't sell or "share" personal information as California law defines those terms.
Children
Tagtwin is not meant for children under 13, and we don't knowingly collect data from them.
Changes to this policy
If we change this policy, we'll update the date at the top. Before Tagtwin collects any new kind of data, or uses data in a new way, we will update this policy and ask for your agreement again in the extension. Nothing new is collected until you agree.
Contact
Tagtwin
hello@tagtwin.com