CanvasBlocker is a Firefox add-on designed to enhance user privacy by preventing websites from utilizing certain JavaScript APIs for fingerprinting. This subscription-based tool offers various modes to either block or fake fingerprinting APIs, including canvas 2D, webGL, and audio. Users can choose to completely block these APIs on all sites, selectively allow them, or employ a default setting that alters the data returned by the APIs to hinder consistent tracking. Additionally, the add-on provides an option to ask for permission each time a protected API is accessed, allowing for customizable privacy control.

With its user-friendly interface, CanvasBlocker makes it easy to navigate through different blocking modes such as allowing only whitelisted sites or blocking those on a blacklist. The add-on aims to provide a balance between privacy and functionality, ensuring that users can browse the web with reduced risk of being tracked while still enjoying a seamless online experience.