Runet Censorship Bypass is a Firefox extension designed to help users circumvent internet censorship in Russia. This free tool allows access to a range of blocked websites, including libraries, encyclopedias, and political sites. It operates by using a PAC-script that connects via specific servers, ensuring only the blocked sites are proxied while leaving the rest of the browsing experience intact. Users are required to allow the extension to run in private windows after installation, which enhances its functionality in restricted environments.

The extension is not without its downsides; it may cause increased CPU usage for each HTTP request made by the browser. Additionally, it uses approximately 30MB of memory to keep users updated on the unblocked sites through an icon that displays the number of accessible domains. The PAC-script is regularly updated every 12 hours, consuming around 6MB of data daily, which is a consideration for users with limited bandwidth.