Castorus is a subscription-based browser extension designed for real estate tracking, specifically tailored for Firefox users. It simplifies the process of monitoring property listings by automatically gathering essential information from the real estate ads you view. Users benefit from features such as price evolution tracking, modification alerts, and links to where the listing has appeared before, along with financing options available for the property.

The community-driven aspect of Castorus allows users to share anonymous real estate insights, providing historical data on listings that others have previously viewed. Additionally, with the introduction of version 2.1, a price analyzer has been integrated, offering real-time pricing information for products on e-commerce sites. Castorus is compatible with Android devices running Firefox version 54 or higher, and it operates exclusively on professional real estate websites to ensure data protection.