Intercept.rest vs Sandbox: What are the differences?
Intercept.rest: Faster API debugging. Similar to the Network tab in Chrome Dev Tools but works for any API, Mobile apps, web hooks, frontend etc.; Sandbox: Quick and easy mock RESTful API and SOAP webservices. Quickly mock RESTful API or SOAP web-services with simple or dynamic responses, and fault injection to simulate real application behaviour.
Intercept.rest and Sandbox can be primarily classified as "API" tools.
Sandbox is an open source tool with 161 GitHub stars and 28 GitHub forks. Here's a link to Sandbox's open source repository on GitHub.