MOBI/AZW3 → FB2
Converting a novel from Kindle / Mobipocket (.mobi, .azw3, .azw) to FictionBook (.fb2) is a routine step in practice — FB2 is a single XML file holding text, metadata and illustrations together, so nothing goes missing in transit. Fortunately Kindle / Mobipocket and FictionBook are structurally close, so there is not much to lose. Below we explain in detail how Kindle / Mobipocket becomes FictionBook and what to watch out for, and the page ends with a converter that does the job right in your browser — nothing is uploaded, the file never leaves your machine.
What is MOBI/AZW3?
The Kindle family (.mobi, .azw3, .azw) is Amazon's proprietary e-book format. It reflows and can carry a table of contents, and it is read mainly on Kindle devices and the Kindle app, or delivered through Send to Kindle. AZW3 supports a reasonable amount of CSS while the older .mobi barely supports any. It is one of the most common proprietary formats in existing libraries — plenty of books bought or downloaded years ago are in it — which is why converting it to something more portable is such a practical need. Read the MOBI/AZW3 format guide
| Extensions | .mobi.azw3.azw |
|---|---|
| Typical use | Reading on Kindle devices and the Kindle app; one of the most common proprietary formats in existing libraries. |
What is FB2?
FB2 (FictionBook) is an open e-book format based on XML. Text, metadata and illustrations all live in a single file, with images embedded as Base64, so one file distributes completely and you never end up with the text present but the images missing. Its structure is simpler than EPUB and therefore easier for readers to implement, and it is most popular in Russian-speaking regions. The drawback is that it supports almost no complex CSS, so it suits text-plus-illustration books rather than titles that depend on fine layout. Read the FB2 format guide
| Extensions | .fb2 |
|---|---|
| Typical use | Russian-language e-books; single-file distribution where embedded illustrations and full metadata matter. |
How to convert MOBI/AZW3 to FB2
.mobi/.azw3 are proprietary Amazon binary containers with no official parsing spec; third-party tools rely on reverse engineering and occasionally fail or drop metadata. AZW3 stores HTML internally, so extracting text is easier than preserving layout.
FB2 requires structured XML body text, Base64-embedded images and metadata inside <description>. It supports almost no CSS, so it suits text-plus-illustration books rather than layout-heavy titles.
Convert MOBI/AZW3 to FB2
KINDLE → FB2
The Kindle formats (.mobi, .azw3, .azw) are Amazon's proprietary binary containers with no public specification, so they cannot be reliably parsed or produced in a browser. This direction needs a desktop e-book tool; the EPUB or TXT you convert can be read in the Kindle app directly.
A novel reader that syncs your progress across every platform
Tide Reader opens TXT and EPUB, detects chapters on import, lays the text out the way you like it, and syncs your reading position across Windows, macOS, iOS and Android. Drop the converted file in and start reading.
Download Tide ReaderTXT and EPUB; local-first reading, with optional cloud sync and WebDAV.