Custos Privacy Policy

Last Updated: September 1, 2026

Custos is a browser extension designed to help users track product prices, availability, variants, and price history across online stores.

Custos is designed to operate without requiring a Custos account or a Custos-operated backend service.

Information Custos Processes

When you choose to track a product, Custos may process information associated with that product, including:

Product page URL
Product name or title
Current price
Previous prices
Target price
Product availability
Product variant information
Product image URL
Store or website information
Tracking preferences
Notification preferences
Date and time of price checks
Price history

This information is used to provide Custos features such as price tracking, price history, target-price alerts, price-drop notifications, and restock notifications.

Where Your Information Is Stored

Custos stores tracked product information and related settings locally within your browser and on your device.

Custos does not require a Custos account.

Custos does not transmit your tracked-product database to a Custos-operated server.

Product Website Access

To determine current product prices and availability, Custos may connect directly from your browser to websites containing products that you have chosen to track.

For example, if you choose to track a product from an online retailer, Custos may request that product page so it can determine whether the price or availability has changed.

These requests are made directly between your browser and the applicable website.

The website you visit or track may receive information normally associated with a web request, such as your IP address, browser information, cookies allowed by the browser, and other information handled according to that website's own privacy practices.

Custos does not control the privacy practices of third-party websites.

Browsing History

Custos is not designed to collect or transmit your general browsing history to a Custos-operated server.

Custos accesses product pages when necessary to provide features requested by the user, such as tracking a selected product or updating product information.

Amazon Product Tracking

For Amazon product pages, Custos may update product information when you visit the applicable product page.

Custos does not currently perform the same scheduled background tracking for Amazon products that may be available for other supported websites.

Notifications

Custos may generate browser notifications when conditions you configure occur, including:

Price drops
Target-price matches
Product restocks
Other tracked-product changes

Notification settings are maintained locally by the extension.

Analytics

Custos does not currently use third-party analytics services to track extension usage.

Custos does not currently send extension usage statistics to a Custos-operated analytics server.

If analytics functionality is introduced in the future, this Privacy Policy will be updated before such functionality is enabled in a publicly distributed version.

Advertising

Custos does not currently include advertising.

Custos does not use advertising trackers.

Custos does not sell personal information for advertising purposes.

Sale of Information

Custos does not sell your personal information.

Custos does not sell your tracked-product information.

Sharing of Information

Custos does not intentionally transmit your locally stored Custos product-tracking database to third parties.

Custos necessarily communicates with third-party product websites when retrieving information from pages that you have chosen to track.

Those websites operate under their own privacy policies and terms.

External Links

Custos may allow you to open external websites, including product pages or shopping-search pages.

Once you leave the extension and access a third-party website, that website's privacy policy and terms apply.

Permissions

Custos may request browser permissions necessary to provide its features.

These may include permissions for:

Local storage
Scheduled background tasks
Notifications
Accessing the active browser tab
Executing product-information extraction logic
Accessing product websites selected for tracking

Custos requests broad website access because users may choose to track products from many different online stores.

This permission is used for product-tracking functionality and is not intended to collect general browsing activity.

Data Retention

Custos retains tracked-product information locally until one of the following occurs:

You remove the tracked product
You clear Custos data
You clear applicable browser extension storage
You uninstall the extension

Browser behavior may affect whether locally stored extension data remains after uninstalling the extension.

Data Security

Because Custos stores its tracking information locally, much of the security of that information depends on the security of your browser, operating system, and device.

Custos does not operate a remote account system containing your tracked-product database.

Children's Privacy

Custos is a general-purpose shopping utility and is not specifically directed toward children.

Custos does not knowingly operate a service designed to collect personal information from children.

Changes to This Privacy Policy

Custos may be updated over time.

If future versions materially change how information is processed, stored, transmitted, or shared, this Privacy Policy will be updated accordingly.

The “Last Updated” date at the top of this policy will reflect the most recent revision.

Contact

If you have questions about this Privacy Policy or Custos, contact:

Email: max@lu-ong.com