Fail2ban - Intrusion prevention framework
HttpMaster - HttpMaster is a professional software tool for testing and debugging HTTP applications, primarily aimed at REST API applications and web services.
SSHGuard - SSHGuard monitors services through their logging activity.
Hoppscotch - Open source API development ecosystem
RdpGuard - RdpGuard allows you to protect your Remote Desktop (RDP), POP3, FTP, SMTP, IMAP, MSSQL, MySQL, VoIP/SIP from brute-force attacks by blocking attacker's IP address. Fail2Ban for Windows.
Request inspector - Debug web hooks, http clients