Tool for quick and easy REST API mocking

Hi guys,

I am looking for some feedback about my side project that I am working on.
I needed a tool to quickly design and mock our REST API. I've used Postman, my teammates suggested me a swagger.io.

Both tools are pretty fine, but both of them missed some features I was looking for:
- possibility to simulate delayed responses (fixed or random delay from given range)
- dynamic responses (using request data in response - querystring, url parameters, headers etc)
- template language in responses
- possibility to add fake data (email, addresses, uuids, names etc) in responses
- request logging, statistics

Thats why I decided to create such tool by myself. It is almost ready and I am looking for a feedback from possible users - would you use such tool?
Lets say it will be available for free (basic version, with some limitations) with premium version available, for a few bucks/month. Would you pay for such tool?
What features may be useful for you in such tool? Thanks in advance for your feedback.