CodeAssistant is a quick and simple desktop application to run code snippets. Have you ever been messing with a new API and you just want to execute one routine to see the output? Just throw your code snippet into CodeAssistant and it will run and display the output. It works on many languages, from C#, C, C++, Go, Python, Ruby, PHP, and it can be easily extended by adding XML config files. CHeck it out and download it for $5.00 here.
HTTP Assistant is a cross-platform REST client for testing web services. You can check out all the features and purchase it for $5.00 here.
This is another cross-platform app that will help you hash and encode text when working with web services. You can grab it here as well.