azw3-to-pdf

README

azw3-to-pdf

Turn Kindle books into PDFs, from a terminal interface or a single command.

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azw3-to-pdf reads .azw3, .azw, .mobi and .prc files and lays them out as PDFs. Everything is built in: the MOBI/KF8 parser, the layout engine and the PDF writer are all part of the binary. There is no Calibre, no Python, no Ghostscript and nothing else to install.

• A file browser in the terminal. Run it with no arguments and pick a book.
• Batch conversion. Select several books, or point it at a folder.
• Layout presets. E-reader, paperback, print, large print and more, or tune every setting yourself.
• Faithful pages. Chapter breaks, headings, illustrations, the cover, hanging indents and justified text, taken from the book's own stylesheet.
• Real PDFs. Selectable text, outline bookmarks from the book's headings, page numbers and document metadata.

Install

go install github.com/jparkerweb/azw3-to-pdf/cmd/azw3-to-pdf@latest

Or clone and build:

git clone https://github.com/jparkerweb/azw3-to-pdf.git
cd azw3-to-pdf
make build

Use

Open the interface and browse for a book:

azw3-to-pdf

Convert one book from the shell:

azw3-to-pdf book.azw3 --no-tui

Convert a whole folder into a separate output directory, four at a time:

azw3-to-pdf ~/Books --recursive --no-tui --output-dir ~/PDFs --jobs 4

Look inside a book without converting it:

azw3-to-pdf probe book.azw3 --verbose

In the interface

Key	Does
enter	Open a folder, choose a book, confirm
space	Add the highlighted book to a batch
b	Convert the batch
tab	Type a path instead of browsing
d	Switch drive (Windows)
h	Jump to your home folder
l / p	Fine-tune the layout / pick a preset
?	Keyboard shortcuts
ctrl+t	Switch between the two colour themes
ctrl+c	Quit

Presets

azw3-to-pdf presets

Preset	Layout
ereader	A5, 11 pt serif, tight margins. The default.
paperback	6 × 9 in with book margins and a running header.
print	US Letter with generous margins for printing.
a4	A4 with standard margins.
compact	Small type and thin margins; about a third fewer pages.
large-print	A4, 16 pt sans, open leading.
phone	A narrow page that fills a phone screen.
manuscript	Double-spaced Letter pages for mark-up.

Any preset can be overridden:

azw3-to-pdf book.azw3 --no-tui \
  --preset paperback \
  --page-size 120x160mm \
  --font-size 12 \
  --line-spacing 1.5 \
  --margin 12 \
  --no-justify

azw3-to-pdf page-sizes lists the built-in sizes. A measurement works too: 120x160mm, 6x9in or 432x648pt.

Fonts

The body text uses a system serif face (Georgia, Times New Roman, DejaVu Serif or Liberation Serif, whichever is found first). --font sans and --font mono pick a system face of that kind, and --font /path/to/Font.ttf uses your own. If nothing suitable is installed, the Go typefaces embedded in the binary are used, so a conversion never fails for want of a font.

Only TrueType (.ttf) files can be embedded. OpenType/CFF (.otf) and font collections (.ttc) are skipped in favour of the next candidate.

Configuration

Settings are read from config.yaml in your configuration directory (azw3-to-pdf version prints the path). Everything is optional:

preset: paperback

output:
  dir: ~/PDFs
  suffix: ""
  conflict: rename   # fail, overwrite, rename or skip

layout:
  page_size: trade
  margin_mm: 18
  font: serif
  font_size: 11.5
  line_spacing: 1.42
  images: true
  cover: true
  title_page: true
  page_numbers: true
  bookmarks: true

ui:
  theme: midnight-ink   # or paper-sepia

Command-line flags override the file, which overrides the preset.

What it understands

Containers	Palm database (.azw3, .azw, .mobi, .prc)
Formats	KF8 (MOBI 8) and MOBI 6, including dual-format files
Compression	None, PalmDOC (LZ77) and HUFF/CDIC
Text	UTF-8 and Windows-1252
Images	JPEG, PNG, GIF and BMP
Styling	The book's own stylesheet: alignment, relative font sizes, hanging indents and page breaks

DRM is not removed. A book bought from the Kindle store and never de-authorised is encrypted, and azw3-to-pdf will say so rather than produce a PDF of noise. Convert books you own in an unencrypted form.

.kfx, the newest Kindle format, is a different container and is not supported.

Development

make build     # build ./azw3-to-pdf
make test      # go test ./...
make lint      # golangci-lint run ./...
make ci        # lint, test and build, as CI does
make run       # build and open the interface
make snapshot  # cross-platform build with goreleaser

Releases are cut by pushing a tag: git tag v0.1.0 && git push origin v0.1.0 runs the tests and then publishes binaries for Linux, macOS and Windows on both amd64 and arm64 through GoReleaser. See CHANGELOG.md for what has changed in each version.

The code is laid out in stages, each of which can be read on its own:

Package	Does
internal/ebook	Palm container, MOBI/KF8 headers, decompression, resources
internal/htmldoc	Book markup and CSS to a flat list of layout blocks
internal/pdfout	Blocks to pages: wrapping, images, bookmarks, fonts
internal/engine	Conversion jobs, output naming, progress
internal/presets	Named layouts
internal/tui	The terminal interface
internal/cli	Flags, subcommands, headless conversion

Licence

MIT.