I've used Fiddler both for capturing existing requests as well as firing off my own to test an API :) You can create one from scratch or modify one that was pre

I've used Fiddler both for capturing existing requests as well as firing off my own to test an API :) You can create one from scratch or modify one that was previously captured (the latter being really handy for dealing with auth and large payloads). Re xplat: they recently announced a cross-platform beta that will replace the Windows-only one in the long-term; I haven't tried it myself though.