Filippo Valsorda (@FiloSottile) is a cryptography engineer building and breaking systems in Go. He works at Google on the Go Open Source Project, where he owns the Go cryptography standard libraries. Previously at Cloudflare, he developed its experimental TLS 1.3 stack and kicked DNSSEC until it became something deployable. Nevertheless, he's probably best known for making popular online vulnerability tests, including the original Heartbleed test.