Cure53

Cure53 is a highly specialized cybersecurity auditing firm based in Berlin, Germany, renowned for their expertise in web security, browser security, and cryptographic protocol review. Founded in 2013 by Dr. Mario Heiderich, the firm has built an exceptional reputation through hundreds of published audit reports for some of the world's most prominent open-source projects and technology companies.

Cure53 is the go-to auditor for VPN providers, password managers, messaging applications, and browser extensions, with their public audit reports becoming a mark of credibility in the privacy and security tool market. The company's expertise extends deep into DOM security, XSS prevention, Content Security Policy, and other web-specific attack vectors that many generalist penetration testing firms lack the depth to properly assess.

Cure53 has audited notable projects including ExpressVPN, NordVPN, 1Password, Bitwarden, Wire messenger, and numerous other privacy-focused tools. Their team combines academic research with practical exploitation skills, and several team members are recognized experts in browser security and web standards. While relatively small compared to large consultancies, Cure53's focused expertise and published track record make them the premium choice for web application and cryptographic security audits.