dxpdf — Fast DOCX to PDF Converter in Rust

Convert Microsoft Word DOCX files to PDF without Microsoft Office, LibreOffice, or any cloud API.

dxpdf is an open-source, standalone DOCX-to-PDF conversion engine written in Rust and powered by Skia. It reads .docx files and produces high-fidelity PDF output — preserving text formatting, tables, images, headers, footers, hyperlinks, and page layout. Available as a CLI tool, a Rust library, and a Python package.

Built by nerdy.pro.

Key Features

• Blazing fast — converts multi-page documents in under 100 ms on modern hardware
• High fidelity — Flutter-inspired measure → layout → paint pipeline with pixel-accurate baseline positioning
• Type-safe — compile-time dimensional type system (Twips, Pt, Emu) prevents unit mixing bugs
• Standalone — no Office installation, no LibreOffice, no external services needed
• Cross-platform — runs natively on macOS, Linux, and Windows
• Three interfaces — use as a CLI tool, Rust library (use dxpdf;), or Python package (import dxpdf)
• ISO 29500 compliant — validated against the Office Open XML specification

Installation

Command-Line Tool

cargo install dxpdf

Rust Library

Add to your Cargo.toml:

[dependencies]
dxpdf = "0.2.4"

Python Package

pip install dxpdf

Usage

CLI — Convert DOCX to PDF from the Terminal

dxpdf input.docx                  # produces input.pdf
dxpdf input.docx -o output.pdf    # specify output path

Rust — Convert DOCX to PDF Programmatically

let docx_bytes = std::fs::read("document.docx")?;
let pdf_bytes = dxpdf::convert(&docx_bytes)?;
std::fs::write("output.pdf", &pdf_bytes)?;

You can also inspect or transform the parsed document model before conversion:

use dxpdf::{docx, model, render};

let document = docx::parse(&std::fs::read("document.docx")?)?;

for block in &document.blocks {
    match block {
        model::Block::Paragraph(p) => { /* inspect paragraph content */ }
        model::Block::Table(t) => { /* inspect table structure */ }
    }
}

let pdf_bytes = render::render(&document)?;

Python — Convert DOCX to PDF in Python

import dxpdf

# Bytes in, bytes out
pdf_bytes = dxpdf.convert(open("input.docx", "rb").read())

# File path to file path
dxpdf.convert_file("input.docx", "output.pdf")

Supported DOCX Features

dxpdf handles the most common DOCX features found in real-world business documents, reports, and forms:

Performance Benchmarks

Benchmarked on Apple M3 Max with hyperfine (20 runs, 3 warmup):

dxpdf processes most business documents in under 100 ms, making it suitable for batch processing, server-side conversion, and CI/CD pipelines.

Building from Source

Prerequisites

• Rust toolchain (1.70+)

• clang (required by skia-safe for building Skia bindings)

• Linux only: libfontconfig1-dev and libfreetype-dev

  sudo apt-get install -y libfontconfig1-dev libfreetype-dev
  

Build

cargo build --release

The release binary will be at target/release/dxpdf.

Run Tests

cargo test

Architecture

dxpdf follows a measure → layout → paint pipeline inspired by Flutter's rendering model:

DOCX (ZIP) → Parse → Document Model → Measure → Layout → Paint → PDF
             Twips/Emu/HalfPoints       ←── Pt throughout ──→   Skia

Type-safe dimensions flow through the entire pipeline: OOXML units (Twips, Emu, HalfPoints) in the parsed model, Pt (typographic points) in layout, and f32 only at the Skia rendering boundary.

Each layout element (paragraphs, table cells, headers/footers) goes through three phases:

1. Measure — collect text fragments, fit lines, produce draw commands with relative coordinates
2. Layout — assign absolute positions, handle page breaks, distribute heights (e.g., vertically merged cells)
3. Paint — emit draw commands at final positions (shading → content → borders)

Module Overview

OOXML Feature Coverage

Validated against ISO 29500 (Office Open XML). 37 features fully implemented, 9 partial, 13 planned.

Text Formatting (w:rPr)

Paragraph Properties (w:pPr)

Styles

Tables

Images

Page Layout

Headers & Footers

Lists

Fields

Other

Dependencies

Frequently Asked Questions

How do I convert a DOCX file to PDF?

Install dxpdf with cargo install dxpdf, then run dxpdf input.docx. The PDF will be created in the same directory. You can also specify an output path with -o output.pdf.

Does dxpdf require Microsoft Office or LibreOffice?

No. dxpdf is a standalone converter that reads DOCX files directly and renders PDF output using Skia. No Office installation or external service is needed.

Can I use dxpdf as a library in my Rust or Python project?

Yes. In Rust, add dxpdf as a dependency and call dxpdf::convert(&docx_bytes). In Python, install with pip install dxpdf and call dxpdf.convert(bytes) or dxpdf.convert_file("input.docx", "output.pdf").

What DOCX features are supported?

dxpdf supports text formatting, paragraphs, tables (including nested and merged cells), inline and floating images, styles with inheritance, headers/footers, lists, hyperlinks, section breaks, and automatic pagination. See the full feature matrix above.

How fast is dxpdf?

On Apple M3 Max, dxpdf converts a typical multi-page business document in under 100 ms. A 24-page image-heavy document takes about 350 ms. It is designed for batch processing and server-side use.

What platforms does dxpdf support?

dxpdf runs on macOS, Linux, and Windows. On Linux, you need libfontconfig1-dev and libfreetype-dev installed.

Contributing

Contributions are welcome. Please open an issue before submitting large PRs.

Built by nerdy.pro.

License

MIT