It uses AMZN Polly for the backend, switching to Wavenet types would cause an 4x price increase (based on current offerings by the majors clouds). It is a bit difficult to justify because that would exceed the cost of an off-the-shelf audiobook from e.g. Audible. I do however plan to add it as an option.

If you have any ideas etc. drop me an email! (See profile)

Indeed, everytime the server goes down (every other week), I have to SSH in and trawl through all the amassed epubs...:D

(The files persist until the conversion is fully complete i.e.uploaded to S3 and sent to user)