Use Exodus Privacy to check Android Apps User trackers Firefox 3 Vivaldi 0 https://reports.exodus-privacy.eu.org/en/ The proposit of OpenSource has nothing to do with privacy and security, but with share and development, security and privacy depends only of the developer itself, irrelevant if it’s OpenSource or not. You can fork Firefox, but if this fork isn’t atended and updated, is less secure than any other browser. Hacker also can read the source and it’s easy to inyect malware in a disatended OpenSource Soft.