I want Spy++ but I don't have Visual Studio

There is WinSpy++ by James Brown at Catch22.net

It's free contains source and works well.

Winspector has been more helpful. Not sure why their site is down right now, but there are a lot of other places to download it.

Visual Studio 2013 now has a community edition. See the Q&A on that page to see if you can use it.

Spy++ is included in the community edition. I had to launch the "Developer Command Prompt for VS2013" and then run the spyxx.exe executable from that command prompt. Searching for "spy++" or "spyxx" in the "Search programs and files" entry box on the (Windows 7) start menu didn't find it.