LibreTranslate - Free and Open Source Machine Translation API ( libretranslate.com )
A Free and Open Source Translation Service. Can translate text and text files(Including Word documents, epubs, and HTML files).
It also includes a simple and well-documented API, Albeit paid.
It can also be self-hosted, giving you the option to run your own API server.
Github link: https://github.com/LibreTranslate/LibreTranslate
ALT