KOReader

KOReader is a document viewer aimed primarily at e-ink readers. It runs on Cervantes, Kindle, Kobo, PocketBook, and reMarkable devices, as well as Android and Linux, with a custom animation-free interface tuned for e-paper screens.

It handles fixed-page formats (PDF, DjVu, CBT, CBZ) and reflowable e-book formats (EPUB, FB2, Mobi, DOC, RTF, HTML, CHM, TXT), and scanned PDF and DjVu files can be reflowed with the built-in K2pdfopt library. The reader view is highly customizable, with arbitrary page margins, line spacing, external fonts and styles, and bundled multi-lingual hyphenation dictionaries.

It integrates with calibre for wireless transfers and OPDS library browsing, and connects to Wallabag, Wikipedia, and Google Translate. StarDict dictionary lookup, RSS feeds, over-the-air updates, an FTP client, an SSH server, and plugins round it out. KOReader is volunteer-developed and licensed under AGPL.