I've found these tools particularly useful if you've got your team divided up into frontend vs backend/platform. We would discuss and mock up the endpoint to unblock the API consumers while the actual service is built.

I use something like this to test webhooks and demonstrate that the service behind it is working.

a simple example is when developing against a third party api, and want to validate the behavior of your code and see what the HTTP request looks like, swap the API endpoints with mockbin urls and check, even mock the response with a Bin and build your client "offline" without hitting API throttling rate limits or exceeding your quotas for paid APIs, and much more :)

hi - we have written a blog post on why/how we use this internally: http://blog.mashape.com/welcoming-mockbin-to-the-mashape-fam...

If you are developing an SPA and want to do front end first.

That's a ton of use cases!