kepubverto — EPUB to KEPUB for Kobo, without breaking the book

[Kayadelenium]

Some of you know epubveri, epubsana and epublift from their threads here. This is the fourth member of the family.

While I was building those three, I converted a lot of books to KEPUB, with kepubify and with epublift's own Kobo conversion, and I checked every result with epubveri. Again and again, a book that was valid before the conversion had errors after it. kepubify is a good program, and it is the reason most of us know what a KEPUB is; I learned the format from it. But I wanted a converter I could trust with any book, so I wrote kepubverto. It is built around one rule: it never makes a book worse.

What it does

It gives a book what a Kobo needs for reading statistics, faster page turns and the proper progress bar, and nothing else. Your text and the rest of the book are left as they were. The span ids are the same as kepubify's, so if you switch, your reading position and highlights should carry over.

kepubverto converts; it does not check or repair. That is the job of epubveri and epubsana, and the planned Sigil and calibre plugins will run them together. kepubverto is built so that a valid book stays valid, and I test that on my whole shelf before every release. On my Kobo, reading position and the progress bar work, both on a converted book alone and at the end of my epublift chain (validate, metadata, optimize, convert).

Why it is safe to point at a real book

• It never writes over your file. book.epub becomes book.kepub.epub next to it.
• An existing output file is replaced only if you ask for it (-f).
• A chapter it cannot convert safely is left exactly as it was, and it tells you which one.
• The web page converts inside your browser. The book is not uploaded anywhere.

How to use it today

Until the plugins exist:

• In your browser, nothing to install: https://veripublica.github.io/kepubverto/ Drop an EPUB on the page and download the KEPUB.
• Command line: binaries for Windows, macOS and Linux on the releases page. The macOS and Windows binaries are not code-signed, so the first run shows the usual warning. Or, with Rust installed: cargo install --locked kepubverto

kepubverto -i book.epub

What it does not do (yet)

kepubify's optional extras (smarten punctuation, hyphenation, extra CSS and the rest) are not in this first version, and I have not decided yet which of them will come. It does not add a dummy title page, and it does not change the book's metadata or cover.

What would help

1. Your device. I have tested on my own Kobo. If yours is a different model or firmware, convert a book and tell me whether position, progress and page turns behave. If you switch a book you already read with kepubify, I would especially like to know whether your highlights and last position come through.

2. A book that came out worse. Anything that opens, looks or behaves differently after conversion. Your original is untouched, so you can compare the two, and epubveri or epubcheck will check the result.

3. Which kepubify option you miss most. That decides which one comes first.

Repo: https://github.com/veripublica/kepubverto

It is AGPL, written in Rust, no Java, no C dependencies.

[JSWolf]

Hyphenation is the most feature important to add next.

What does kepubverto do that the KePub conversion in the KoboTouch driver doesn't do?

[DNSB]

For my uses, I only used kepubify to add the kobo spans, etc. For hyphenation, smartening punctuation, CSS and find/replace are items that I use other tools for.

Since my preferred layout for reading is left justified, hyphenation is more or less a matter of theoretical interest to me.

Currently, I am not using the calibre option to send kepubs to my Kobo Libra Colour. Unless you change settings, the RMSDK renderer is now used for DRMmed ePubs only with Kobo's TENG renderer being used for kepub, epub and LCP DRMmed ePubs.

As for what TENG stands for? I haven't seen an answer from Kobo but I've seen Tolino ENGine renderer and The Epub Next Generation renderer as possible answers.