Your files stay on your Mac.
FictionBook (.fb2) files use an open XML structure designed for e-readers that Kindle cannot open natively. Convertessa rewrites that structure into Kindle's MOBI format, mapping chapter sections, inline styles, and embedded cover art into the fields Kindle apps and devices understand. The result is a .mobi file ready to side-load or transfer directly to your Kindle.
Drag one .fb2 file or an entire folder of FictionBook titles onto Convertessa. All files stay on your Mac — nothing is uploaded.
Pick Kindle MOBI from the output format list. Because MOBI supports embedded images, you can set quality for any cover art or illustrations carried in the source file.
Click Convert. Convertessa writes the .mobi file alongside the original. Transfer it to your Kindle device or open it in the Kindle app.
Images, audio, video, documents, archives and eBooks — all converted natively, right on your Mac.
Pick a format you have — see everything Convertessa can turn it into.
Convert hundreds of files at once with per-type group defaults and individual overrides.
First-class support for HEIC, AVIF and WebP — encode and decode, both ways. Read JPEG XL and a dozen more modern formats too.
Drop files anywhere on the window. Native, instant, and exactly what you’d expect on a Mac.
Dial in compression, resolution and bitrate. Keep originals pristine or shrink for sharing.
Never overwrite a file by accident. Convertessa appends safe suffixes automatically.
Every job is logged locally. Re-run a previous conversion or revisit recent outputs in a click.
Bundle your converted files straight into a single ZIP, TAR or 7z — packaged and ready to share the moment a job finishes.
Right-click any file in Finder and choose Convert. A Quick Action handles it on the spot — no need to open the app first.
Shrink Convertessa to a tidy mini window that tucks into a corner — just a drop zone and a format picker for quick, one-off conversions.
No cloud. No account. No upload. Every conversion happens entirely on-device, using the power already in your Mac. What you convert is nobody’s business but yours.
Script conversions, wire them into your build, or batch a folder from the terminal. The same engine, no GUI required.
Read the full CLI documentation →Shrink Convertessa down to a small, focused window — drop, convert, done, with your recent conversions one click away.
macOS 14+ · Apple Silicon & Intel
New formats, new features, and fixes — every release, on the record.
Yes. Convertessa maps FictionBook's <section> and <title> elements to the MOBI chapter structure, so Kindle's built-in table of contents is populated automatically.
Document metadata — author name, book title, description — is carried into the MOBI file so Kindle displays it correctly in your library. EXIF data embedded in any cover art or inline images is stripped.
Yes. Drag a folder onto Convertessa or run convertessa ./library/ --to mobi in the terminal. Every .fb2 file in the folder is converted and the .mobi files are written alongside the originals.