jacklittleton uses Paw
Paw allows me to interface with an API prior to starting UI work that requires the API. This helps me understand what data is required to be sent to the API, and what to expect back.
In cases where I develop the API, Paw helps me to test as I'm developing, ensuring changes I make aren't breaking other parts of the API.
nickdecooman uses Runscope
Used Runscope for monitoring API uptime and data validation in context of the Harald beacon platform.