kob

Self-hosted article-to-EPUB service. Paste a URL, get an EPUB on your e-reader.

Designed to be browsed from the e-reader: HTML-only, no JavaScript, big fonts, full-width, paginated (no scrolling).

How it works

1. You browse to the site from your e-reader.
2. Paste an article URL into the input.
3. The server fetches it via Jina Reader, converts to EPUB, and saves it.
4. The article appears in the list — tap to download.

Images are downloaded and embedded into the EPUB at build time, so the file is fully self-contained — no internet needed when reading. If a particular image fails to fetch, it's skipped and the URL is left in the src (so it works online but shows broken offline); a message is written to stderr.

Long articles are split into multiple xhtml files inside the EPUB so weak readers paginate faster (each "chapter" is loaded and laid out independently). Splitting prefers H2/H3 boundaries when present (TOC entries use the heading text) and falls back to "Part 1, Part 2, …" splits at paragraph boundaries when the article has no headings or its sections are larger than the threshold. Tune via EPUB_SPLIT_THRESHOLD_BYTES / EPUB_SPLIT_TARGET_BYTES (see below).

Quick start (Docker)

docker build -t kob .

docker run -d \
  --name kob \
  -p 8080:8080 \
  -v $(pwd)/data:/data \
  -e ARTICLES_PER_PAGE=8 \
  kob

Then point your e-reader's browser at http://<server-ip>:8080.

Environment variables

Var	Default	Purpose
DATA_DIR	/data	Where articles + index.json are stored.
ARTICLES_PER_PAGE	8	How many articles per page on the listing.
JINA_API_KEY	(unset)	Optional. Sent as Authorization: Bearer ... to Jina.
PORT	8080	HTTP port inside the container.
EPUB_SPLIT_THRESHOLD_BYTES	50000	If an article's source markdown is larger than this, it gets split into multiple xhtml files inside the EPUB. Helps weak readers paginate faster.
EPUB_SPLIT_TARGET_BYTES	25000	Target size for each chunk when splitting.

Volumes

Path	Purpose
/data	Article storage. Persist this — losing it loses your library.

Layout inside the volume:

/data/
  index.json
  articles/
    <id>/
      article.epub
      source.md
      meta.json

Security note

There is no authentication. Designed for a trusted home network. If you expose this beyond your LAN, put it behind a reverse proxy with auth (e.g. Caddy + basic auth, or Tailscale).