kobofix web — browser-based EPUB Kobo-fixer

A 100% client-side version of kobofix. The user drags in an .epub, sees exactly what breaks on Kobo (Adobe RMSDK), and downloads a repaired file — and the book never leaves their browser (no server, no upload). Perfect for a free GitHub Pages tool for writers and publishers.

It runs the same engine as the Python CLI, ported to JavaScript and verified to produce byte-for-byte-equivalent fixes and EPUBCheck-clean output.

Files

The deployable site is just five files (no build step, no framework):

index.html        UI + styles
app.js            browser glue (file picker, report rendering, download)
kobofix.js        EPUB pipeline + JSZip glue   (ES module)
kobocss.js        the CSS engine, ported from kobofix.py   (ES module)
vendor/jszip.min.js   JSZip 3.10.1 (zip read/write), vendored so there's no CDN dependency

Everything else in this folder (node_modules/, test/, package.json) is for local development/testing only and is not deployed.

Run locally

# from the repo root
python -m http.server 8000
# open http://localhost:8000/web/index.html

(ES modules require HTTP, not file://.)

Test (Node)

node_modules carries JSZip for a headless parity test that runs the browser engine in Node and checks it against the Python CLI + OCF correctness:

cd web
npm install          # once
node test/run.mjs

There's also an in-browser self-test at web/test/selftest.html.

Deploy to GitHub Pages

Automatic (recommended): the repo includes .github/workflows/pages.yml, which assembles a clean site (just the five files above) and publishes it. In your repo: Settings → Pages → Build and deployment → Source: GitHub Actions, then push to main. Your tool will be live at https://<user>.github.io/<repo>/.

Manual: copy index.html, app.js, kobofix.js, kobocss.js, and vendor/jszip.min.js into a docs/ folder (or a repo root) and enable Pages → Deploy from a branch → /docs.

How it maps to the CLI

| CLI | Web | |---|---| | kobofix --check book.epub | the report shown on screen (KOBO-* ids, line numbers) | | kobofix book.epub | the Download fixed EPUB button | | EPUBCheck merge | not bundled (EPUBCheck is a 12 MB Java app); the report links the two conceptually |

The web app deliberately does not run EPUBCheck (it's a Java tool, not browser-portable). It covers the Kobo/RMSDK layer EPUBCheck can't see; run the CLI or the desktop EPUBCheck for spec conformance.

Browser support

Needs a modern browser (ES modules, File.arrayBuffer, regex lookbehind): Chrome/Edge 80+, Firefox 78+, Safari 16.4+. All processing is local and synchronous-ish; very large books (tens of MB with images) take a few seconds.