Arthur Edelstein is a software engineer focused on human wellbeing. At Tor, he introduced stream isolation, where Tor Browser uses a separate circuit for each website you visit. At Firefox, he was the product manager for the teams that developed Total Cookie Protection and HTTPS-Only Mode. At Brave, he introduced HTTPS by Default and co-authored a paper on the Pool-Party Attack on privacy. In 2021, he published PrivacyTests.org, a project to hold web browser makers accountable for their leaks of private information. He also co-created Project Timestamper, which is an ongoing effort to preserve the authenticity of human knowledge and culture in the age of AI.