boko 0.1.0

Fast ebook conversion library for EPUB and Kindle formats
Documentation

boko

CI crates.io docs.rs

A fast, lightweight Rust library for converting between EPUB and Kindle (AZW3/MOBI) ebook formats.

Features

  • Fast: 100-200x faster than calibre's ebook-convert
  • Lightweight: Pure Rust with minimal dependencies
  • Complete: Preserves metadata, table of contents, images, fonts, and CSS
  • Flexible: Use as a library or command-line tool
  • Cross-platform: Native binaries for all platforms, plus WebAssembly for browsers

Performance

Benchmarks converting a 450KB ebook on an AMD Ryzen 9 7950X:

Conversion boko calibre Speedup
EPUB → AZW3 4.5 ms 1,039 ms 230x
AZW3 → EPUB 3.2 ms 564 ms 176x

Installation

Requires Rust nightly (uses edition 2024 features).

CLI

rustup default nightly
cargo install boko

Library

[dependencies]
boko = { version = "0.1", default-features = false }

Usage

Command Line

# Convert EPUB to AZW3
boko book.epub book.azw3

# Convert AZW3/MOBI to EPUB
boko book.azw3 book.epub

# Show book metadata
boko -i book.epub

Library

use boko::Book;

// Open and convert with automatic format detection
let book = Book::open("input.epub")?;
book.save("output.azw3")?;

For explicit format control (Format: Epub, Azw3, Mobi):

use boko::{Book, Format};

let book = Book::open_format("input.bin", Format::Mobi)?;
book.save_format("output.bin", Format::Azw3)?;

Free functions are also available:

use boko::{read_epub, write_mobi};

let book = read_epub("input.epub")?;
write_mobi(&book, "output.azw3")?;

Creating Books Programmatically

use boko::{Book, Metadata, TocEntry};

let mut book = Book::new();
book.metadata = Metadata::new("My Book")
    .with_author("Author Name")
    .with_language("en");

// Add content
book.add_resource(
    "chapter1.xhtml",
    b"<?xml version=\"1.0\"?>
      <html><body><h1>Chapter 1</h1><p>Hello, world!</p></body></html>".to_vec(),
    "application/xhtml+xml"
);
book.add_spine_item("ch1", "chapter1.xhtml", "application/xhtml+xml");
book.toc.push(TocEntry::new("Chapter 1", "chapter1.xhtml"));

// Save as EPUB or AZW3
book.save("my-book.epub")?;
book.save("my-book.azw3")?;

Web App

A browser-based converter is available at zacharydenton.github.io/boko. All conversions happen locally in your browser using WebAssembly.

Supported Formats

Format Read Write
EPUB 2/3 ✓ ✓
AZW3 (KF8) ✓ ✓
MOBI ✓ ✓*

*MOBI output uses the modern KF8 format (same as AZW3).

Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.

License

MIT