FBReader is an open source application, and as result all the currently supported formats are open. This means FBReader can not open any DRM-protected book, sorry.

  • ePub. At the moment we consider ePub as one of three most important formats. (Two others are mobi and fb2.) FBReader supports all the main features of this format except the tables. CSS support is not full.
  • ePub 3. FBReader does not support most of ePub 3 specific features. We will add some popular features into our ePub code, but ePub 3 standard is huge and we do not plan to support it fully.
  • Mobi (a.k.a. Kindle format, azw3). FBReader opens non-encrypted *.mobi files. DRM-protected are not supported.
  • FB2. From practical point of view, version 2.0 of the format specification is fully supported. To be compliant with version 2.1 of the standard, FBReader lacks support of tables. On the other hand, as far as we know at the moment FB2.1 is not used for real books.
  • PDF.
    • Android: Since version 2.0 FBReader opens PDF file via separate plugin. This plugin uses a third-party library and does not support all the FBReader features.
    • Other platforms: PDF is not supported at this moment.
  • DjVu.
    • Android: Since version 2.0 FBReader opens DjVu file via separate plugin.
    • Other platforms: DjVu is not supported at this moment.
  • HTML. Generally speaking, HTML is not a book format. It has many elements that are related to the visual rendering, while it lacks elements related to the book structure (as result, it's quite impossible to determine a table of contents for an arbitrary book in HTML format). FBReader has limited support for HTML, however it proved to be sufficient for the majority of books available out there.
  • Plain text. This format is supported. However FBReader might not always correctly split text into paragraphs.
  • RTF, DOC (Microsoft Word). FBReader supports some subsets of RTF and MS Word Doc.
  • Plucker.
    • Android: not supported at this moment
    • Other platforms: This format has commands for “absolute positioning”, which are targeted to the devices with specific screen resolution (e.g. “put the item 2 pixels away from the left border”.) Since FBReader aims to allow reading on devices with different screen sizes and resolutions, such commands may be interpreted depending on the context and, in some cases, be completely ignored.
  • CHM.
    • Android: Not supported at this moment
    • Other platforms: There's no complete open description of this format, while there is an open source library called chmlib that allows to work with the format as well as many open source applications that use this library to read and render files in this format. FBReader's support is implemented independently from chmlib as result rendering might be different.
  • LIT (Microsoft Reader format). This format is not supported and is unlikely to be ever supported. It is a closed format created and owned by Microsoft and any attempts to support it would be quite questionable from legal point of view. In the other hand, Microsoft has discontinued their Reader, so there will be no new books in .LIT format. Try to use convertLit program to covert your files into ePub.