Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
Acunetix - Audit your website security and web applications for SQL injection, Cross site scripting and other...
Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
Shodan - Shodan is the world's first search engine for Internet-connected devices.
Postman - The Collaboration Platform for API Development
Intruder - Intruder is a security monitoring platform for internet-facing systems.