About ebooknexus

Free ebook tools that run entirely in your browser. No uploads, no accounts, no waiting for a server.

The tools

• Mobi to Epub converts Kindle Mobi and Azw3 books (without DRM) into standard Epubs that open in any reader.
• The metadata editor fixes titles, authors, series and descriptions so books sort correctly in your library.
• The checker validates an Epub against the real specification rules, explains each problem in plain language with the source line, and can repair the mechanical ones with one click.
• For reading on a Kobo, our sister site kepubify.com converts Epub to Kepub.

How it works

Each tool is a small program written in C and compiled to WebAssembly. Your browser downloads the program once and runs it locally, so your books are processed on your own machine and never uploaded. That is also why the tools are fast: there is no round trip to a server, and a full novel converts or checks in well under a second.

The checker's validation rules are generated from the same RELAX NG schemas the official Epubcheck uses, so its results track the real specification rather than a loose approximation.

Privacy

Covered in one line: your files never leave your device. The longer version is on the privacy page.

Contact

Found a bug, or a book the tools get wrong? Write to hello@ebooknexus.com.