EPUB
EPUB e-book
EPUB is the open standard for e-books. Text reflows to fit any screen, and most e-readers and reading apps support it; Kindle accepts EPUB through Send to Kindle.
Extensions: .epub
Convert EPUB files to MOBI on Windows 10 and 11: free, offline and in batches. Drag the files onto MOBI in Filee's format donut and the MOBI files appear next to the originals.
In File Explorer or on the desktop, select one EPUB file or as many as you like. The first time, Filee offers to download Calibre, the free engine it uses for this conversion.
Hold Ctrl (or the key you set in Filee) and drag the files. A donut of formats opens at the cursor. Prefer menus? Right-click and choose Convert with Filee.
Release the files over MOBI. A progress ring counts up, and each MOBI file is saved next to its original.
Writing MOBI and AZW3 is done by Calibre, the well-known e-book toolkit. Current Kindles also accept EPUB through Send to Kindle, so MOBI is mainly useful for older Kindle devices and apps.
EPUB e-book
EPUB is the open standard for e-books. Text reflows to fit any screen, and most e-readers and reading apps support it; Kindle accepts EPUB through Send to Kindle.
Extensions: .epub
Kindle / Mobipocket e-book
MOBI is the older Mobipocket e-book format that Amazon Kindle used for years. It is still common in older e-book collections, but Amazon has moved to AZW3/KFX and EPUB.
Extensions: .mobi
Filee is a free, open-source file converter for Windows 10 and 11. It works offline and converts 180+ formats with one drag and drop.
Download for Windows