Amazon Echo or Google Home, developer kit capability?

Before buying one of those little awesome object I want to get a simple answer about the allowing capacity with the developer tools.

• Is it allowed to receive the text request in my "skill" or "action"
• Use a bot NPL API like Recast.AI, API.AI, Wit.AI or whatever
• Do any kind of treatment on database
• And finally send a simple text answer to the object

Basically I would like to build a bot but I'm wondering which kind of restriction they put in the developer kit?

Not sure for Google Home but regarding Amazon Echo you can use this hack from init.ai, you can follow this tutorial to add custom NLP to your Echo : https://blog.init.ai/alexa-can-you-add-custom-nlp-to-amazon-echo-b743606906f5#.3aim7p72f