For Cortana!
Cortana Devices SDK:
Cortana Skills Kit:
https://blogs.windows.com/buildingapps/2016/12/13/cortana-skills-kit-cortana-devices-sdk-announcement/#PJwh3kkso647IhgB.97
For Chat Bots.
Microsoft Bot Framework:
Bot Framework SDK
New Azure BOT service!
Azure Bot Services