We use several speech recognition engines in parallel, including customized Sphinx. We don't use deep learning acoustic models yet, but that's in the works.

Off topic but a question regarding text to intent object parsing:

Is there any date entity in the wit directory? How do I parse a date for e.g. 17th Feb or feb 27 or 13/02?

Datetime only has contextual date selection i.e. today or tomorrow.

`wit/datetime` does parse both absolute dates like "17th Feb", "feb 27" or "13/02", and relative dates like "tomorrow". If you find a date that is not parsed that's a bug.