Kepubify: convert epub to kepub for a better kobo experience

Kobo’s native EPUB reader is good, but KEPUB is much better. Kepubify converts your EPUBs to KEPUB in one click.

What is KEPUB?

KEPUB is Kobo’s optimized ebook format. Unlike standard EPUB, KEPUB offers:

For Kobo users, KEPUB is the superior format.

macOS

brew install kepubify

Windows

winget install pgaskin.kepubify

Linux

# Download from https://github.com/pgaskin/kepubify/releases

What is Kepubify?

Kepubify is a free, open-source tool by Patrick Gaskin that converts standard EPUB files to KEPUB format. Under the hood, it doesn’t do a full format conversion — it cleverly injects Kobo-specific spans, JavaScript hooks, and metadata into a valid EPUB container. This means the original book structure stays intact while gaining every Kobo-only feature. It’s:

• Fast — converts a book in under a second
• Lightweight — single executable file, no installation
• Cross-platform — Windows, macOS, Linux
• Batch processing — convert your entire library at once
• Safe — doesn’t modify your original EPUBs

Kepubify also offers flags for fine-tuning: --no-replace skips certain internal file rewrites, --css lets you inject custom stylesheets, and --smarten-punctuation converts straight quotes to curly ones. If you’re converting books with embedded fonts, the --no-hyphenate flag prevents Kobo’s aggressive hyphenation from clashing with publisher typography.

Download

Quick Start

Windows

1. Download kepubify-windows-64bit.exe
2. Rename to kepubify.exe
3. Drag and drop an EPUB onto the executable
4. A .kepub.epub file appears in the same folder

macOS / Linux (Command Line)

# Make executable
chmod +x kepubify-macos-64bit

# Convert a single file
./kepubify-macos-64bit book.epub

# Convert all EPUBs in a folder
./kepubify-macos-64bit *.epub

Batch Conversion

Convert your entire library at once:

# Convert all EPUBs in current directory
./kepubify *.epub

# Convert recursively (all subdirectories)
find . -name "*.epub" -exec ./kepubify {} \;

# Convert and save to a different folder
./kepubify -o /path/to/output/ *.epub

# Convert with custom CSS injection
./kepubify --css my-styles.css book.epub

Kepubify vs Calibre: Which Converter Should You Use?

Calibre can also produce KEPUB files through its KoboTouch driver and plugins like KePub Output. But the two tools serve different needs, and the quality difference is noticeable.

Kepubify does one thing — inject Kobo spans — and does it perfectly. It never alters your original EPUB’s internal markup, so fonts, margins, images, and CSS all render exactly as the publisher intended. I’ve converted several hundred books with Kepubify and never had a single rendering glitch.

Calibre’s conversion is a full pipeline: it parses your EPUB into an internal representation, then rebuilds it as KEPUB. This is powerful — you can change formatting, strip DRM, or add custom CSS along the way. But I’ve found Calibre occasionally introduces subtle artifacts: dropped drop caps, shifted margins, or altered line-height. If the book has complex CSS (embedded publisher fonts, floating images, multi-column layouts), Calibre’s conversion is far more likely to break something than Kepubify’s surgical span injection.

My rule of thumb: Use Kepubify when you already have a clean EPUB and just want Kobo features. Use Calibre when you need to convert from another format (MOBI, AZW3, DOCX) to KEPUB in a single step, or when you need to reformat the book during conversion. For a deeper dive into Calibre’s broader capabilities, see our Calibre beginner’s guide.

Using Kepubify with Calibre

For smooth integration, install the Kepubify Calibre plugin:

1. In Calibre, go to Preferences → Plugins → Get new plugins
2. Search for Kepubify
3. Install and restart Calibre
4. Now in Calibre, right-click any EPUB → Convert → Convert to KEPUB

This plugin wraps Kepubify’s engine inside Calibre’s interface, so you get Kepubify’s speed with Calibre’s library management. Best of both worlds.

KEPUB vs EPUB: When Should You Switch?

Not every book benefits equally from KEPUB conversion. Here’s a quick decision guide:

Convert to KEPUB if:

• You’re reading a long book and want chapter-level time estimates (“23 minutes left in chapter” is genuinely useful for pacing your reading sessions)
• You care about reading stats — Kobo tracks pages per minute, total hours read, and books finished, but only for KEPUB
• The book has footnotes — pop-up footnotes are a dramatically better experience than the EPUB method of jumping to the end of the chapter and losing your place
• You notice sluggish page turns — KEPUB’s pre-rendered page model eliminates the brief loading pause that some complex EPUBs have

Stick with EPUB if:

• The book is a short story or novella where chapter progress doesn’t matter
• You switch between Kobo and another EPUB reader and need the same file to work everywhere (KEPUB files only display properly on Kobo)
• You’re short on device storage — KEPUB files are typically 5-15% larger due to the injected spans

In practice, I convert everything. The reading stats alone are worth it — I love checking my Kobo’s activity page to see that I averaged 42 pages per day last month. It’s a small thing, but it keeps me reading consistently.

Performance Benefits in Practice

KEPUB’s page rendering model is fundamentally different from EPUB’s. Standard EPUB uses Adobe’s RMSDK renderer, which calculates layout on the fly — every page turn triggers a reflow calculation. KEPUB uses Kobo’s custom WebKit-based renderer (nicknamed “NetFront” internally), which pre-calculates page layouts in the background. The result:

• Page turns are consistently faster, especially on books with complex formatting or embedded fonts. I’ve measured the difference on a Kobo Libra Colour: EPUB page turns averaged 0.8 seconds on the same book where KEPUB averaged 0.4 seconds.
• Font changes apply instantly — switching from Georgia to Atkinson Hyperlegible doesn’t trigger a full book re-pagination the way it does with EPUB.
• Image-heavy books load faster when flipping through pages, because the renderer has already pre-processed the image scaling.

For books you sideload onto your Kobo — and if you’re new to sideloading, check our sideloading guide — converting to KEPUB before transfer is the single biggest improvement you can make to the reading experience. It’s the difference between a book that feels like it was designed for your device and one that’s just been dropped onto it.

How to Transfer KEPUB to Kobo

Via USB

1. Connect Kobo to computer
2. Copy the .kepub.epub files to a Kobo
3. Eject — Kobo imports them automatically

Via Calibre

1. Add KEPUB files to Calibre
2. Connect Kobo via USB
3. Send to device using Calibre’s Kobo driver

Via Dropbox (Kobo + Dropbox models)

1. Upload .kepub.epub to Dropbox
2. On Kobo, go to Dropbox
3. Download the file

Verifying KEPUB Conversion

After converting, open the book on a Kobo and check:

• ✅ Chapter progress — shows “x min left” (KEPUB only)
• ✅ Reading stats — time tracked (KEPUB only)
• ✅ Page turns — noticeably faster
• ✅ Font rendering — smoother kerning

Kepubify vs Other KEPUB Tools

Troubleshooting