Really rough and basic php PDF to Kindle converter using k2pdfopt.
Try it out! https://pdftokindle.herokuapp.com/ (Only small filesizes <100kb work on Heroku because of its RAM restrictions)
Running it is easy!
docker run -d -p 8080:8080 agusalex/pdftokindle
Default Max size for PDF is : 300MB To change this set:
PHP_FPM_UPLOAD_MAX_FILESIZE=max_sizeM
SERVER_MAX_BODY_SIZE=max_sizeM
For complete list of enviromental variables check behance/docker-php
https://hub.docker.com/repository/docker/agusalex/pdftokindle