FB2 Reader opens FictionBook ebooks directly in your browser, with nothing to install and no account. Drop in an .fb2 file or an .fb2.zip archive and start reading: the table of contents lists every part and chapter, the arrow keys and the Previous and Next buttons move through the book, and full text search finds any word or phrase. Footnotes work as links, so tapping a note number takes you to the note and the back button returns you to the text. You can switch between light, sepia and dark themes, pick a serif or sans serif font, and change the text size, line spacing and page width, and the reader remembers your settings and the place where you stopped in each book. Cyrillic books saved in windows-1251 or KOI8-R display correctly because the file is decoded with the encoding it declares. The book is read in your browser and never uploaded, and its content is cleaned and shown in a sandboxed frame. To keep a copy that opens in other apps convert it with FB2 to EPUB Converter, and to print it use FB2 to PDF Converter.
FB2, short for FictionBook 2, is an XML ebook format that grew up with Russian online libraries in the early 2000s. It became popular because one plain file holds the whole book, text and pictures together, and because its markup describes meaning rather than appearance: a section is a chapter, a title is a title, a poem is made of stanzas and verse lines, and a note is a note. That makes FB2 books easy to catalogue and convert, but most reading apps outside Eastern Europe never added support, so Apple Books, Kindle and Google Play Books cannot open them, and Windows has no built-in FB2 viewer. Opening an FB2 in a browser is the quickest way around that. This reader converts the FB2 structure into EPUB chapters in memory, then shows them with the same engine as the EPUB Reader: sections become chapters in the contents list, base64 images stored inside the file are decoded back into pictures, and the notes body becomes a chapter that note numbers link to. Because the conversion happens on your device, even large libraries of personal books can be read without sending anything to a server. Most FB2 files from older sites are encoded in windows-1251 rather than UTF-8. A reader that assumes UTF-8 shows those books as unreadable symbols, so this one always checks the encoding declared at the top of the file first.