Winspector Spy - Have you ever used Spy++ that comes with MSVC?

ServerSuit - ServerSuit is a browser based program that enables remote Linux administration, monitoring, website hosting, and server setup automation.

Window Detective - Window Detective is a programmer's tool used to "spy" on an application's windows...

Netumo - Ensure healthy website performance, uptime, and free from vulnerabilities. Automatic checks for SSL Certificates, domains and monitor issues with your websites all from one console and get instant notifications on any issues.

WinSpy - Retrieve window information.

AppZero - AppZero is a monitoring and migration tool that allows users to keep track of different applications and servers in both simple and complex IT environments.