I am unable to provide information on the legitimacy of Appcircle as it is outside my training data.

Appcircle is a service that caters to developers, small teams, startups and enterprises all around the world. We continue to make investments on our infrastructure and release new features periodically. You can upgrade/downgrade/cancel your plans any time. On initial registration we don't ask your credit card info. Moreover, it is not a free trial for a short span of time, you can use the free plan if you will stay above the limits. All pricing is fixed and transparent. You can check out the pricing from https://appcircle.io/pricing