docxide-pdf

⚠️ Work in progress. This is in no way ready for use in production. The API, output quality, and supported features are all actively changing.

A Rust library and CLI tool for converting DOCX files to PDF, with the goal of matching Microsoft Word's PDF export as closely as possible.*

*Reference PDFs are generated using Microsoft Word for Mac (16.106.1) with the "Best for electronic distribution and accessibility (uses Microsoft online service)" export option.

Goals

Accurate: Given a .docx file, produce a .pdf that is visually identical to what Word would export.

Fast: Typical conversions complete in under 100ms.

Small files: Output PDFs should be the same size or smaller than Word's export.

AI useage disclaimer 🤖

While the idea, architecture, testing strategy and validation of output are all human, the vast majority of the code as of now is written by Claude Opus 4.6 with access to the PDF specification (ISO-32000) and the Office Open XML File Formats specification (ECMA-376).

Supported features

• Text: font embedding (TTF/OTF/TTC), bold, italic, underline, strikethrough, double strikethrough, font size, text color, superscript/subscript, small caps, all caps, character spacing, text expansion/compression (w:w), hidden text (w:vanish)
• Paragraphs: left/center/right/justify alignment, space before/after, line spacing (auto, exact, at-least), first-line and hanging indentation, left/right indentation, contextual spacing, keep-next, keep-lines, paragraph borders (top/bottom/left/right/between) with color, paragraph shading, run highlighting
• Styles: paragraph and run style inheritance (basedOn chains), document defaults from docDefaults, theme fonts and colors
• Lists: bullet and numbered lists with multi-level nesting, custom number formats, list style inheritance
• Tables: column widths with auto-fit, merged cells (horizontal gridSpan and vertical vMerge), row heights (exact and minimum), per-cell borders with color/width, cell shading, vertical alignment, cell margins
• Images: inline JPEG/PNG embedding with sizing and alpha transparency, anchored/floating images (all wrap modes), floating image positioning relative to page/margin/column
• Text boxes: DrawingML textboxes (wps:txbx) and VML fallback (v:textbox), shape fills (solid color with theme color support including lumMod/lumOff), textbox body margins
• Page layout: page size, margins, document grid (linePitch), explicit page breaks, pageBreakBefore, automatic page breaking with widow/orphan control
• Sections: multiple sections with nextPage/continuous/oddPage/evenPage breaks, per-section page size and margins
• Multi-column layout: 2+ columns with custom widths and spacing, column breaks, column separators
• Headers/footers: default and first-page variants, per-section headers/footers, page number and page count fields, images in headers/footers
• Footnotes: footnote references, footnote rendering at page bottom with separator line
• Tab stops: left, center, right, decimal with leader dots
• Fonts: cross-platform font search (macOS/Linux/Windows), embedded DOCX font extraction and deobfuscation, font subsetting (CIDFont/Type0), disk-cached font index
• Output optimization: font subsetting, content stream compression

Not yet supported

• Text: kerning (GPOS), ligatures, complex script shaping (Arabic, Devanagari, etc.), CJK fallback fonts
• Tables: conditional formatting (tblLook/tblStylePr — banded rows, first/last column styles), nested tables, floating/positioned tables (tblpPr), text direction in cells (textDirection)
• Images: text wrapping around floating images/textboxes, EMF/WMF vector images
• Layout: distribute alignment (w:jc val="distribute"), vertical page alignment (w:vAlign on section), right-to-left (bidi) text
• Features: clickable hyperlinks (parsed but not linked in PDF), bookmarks, table of contents (field codes), endnotes, charts, SmartArt, OLE objects, structured document tags (w:sdt), mc:AlternateContent fallback
• Fonts: intelligent font substitution (currently falls back to Helvetica when a font is missing)

Examples

See more examples in the showcase

Installation

# Install the CLI
cargo install docxide-pdf

Usage

CLI

# Convert a DOCX file to PDF
docxide-pdf input.docx

# Specify output path (defaults to input.pdf)
docxide-pdf input.docx output.pdf

Library

cargo add docxide-pdf --no-default-features

This avoids pulling in the CLI dependency (clap).

use docxide_pdf::convert_docx_to_pdf;
use std::path::Path;

convert_docx_to_pdf(
    Path::new("input.docx"),
    Path::new("output.pdf"),
)?;

Configuration

Environment Variables

Font scanning results are cached to disk (per-directory, invalidated by mtime). The cache is stored at:

• macOS: ~/Library/Caches/docxide-pdf/font-index.tsv
• Linux: $XDG_CACHE_HOME/docxide-pdf/font-index.tsv (default ~/.cache/)
• Windows: %LOCALAPPDATA%\docxide-pdf\cache\font-index.tsv

Architecture

src/
  lib.rs              — public API
  main.rs             — CLI binary (behind `cli` feature)
  error.rs            — Error enum
  model.rs            — Document/Section/Paragraph/Run intermediate representation
  fonts.rs            — font discovery, metrics, subsetting
  docx/
    mod.rs            — DOCX ZIP + XML → Document parser, shared utilities
    styles.rs         — theme, style parsing, style inheritance
    runs.rs           — run-level XML → Vec<Run>
    numbering.rs      — list/numbering parsing, counter management
    images.rs         — image extraction (inline + floating)
    textbox.rs        — textbox parsing (DrawingML + VML)
    embedded_fonts.rs — DOCX font extraction and deobfuscation
    sections.rs       — section properties, columns, headers/footers refs
    headers_footers.rs— header/footer/footnote XML parsing
  pdf/
    mod.rs            — main render loop, header/footer rendering
    layout.rs         — text layout, line building, paragraph rendering
    table.rs          — table layout, auto-fit, table rendering
tests/
  visual_comparison.rs  — Jaccard + SSIM comparison against Word reference PDFs
  text_boundary.rs      — page/line-level text boundary tests
  fixtures/<case>/      — input.docx + reference.pdf pairs
  output/<case>/        — generated.pdf, screenshots, diff images
tools/
  analyze-fixtures      — fixture score table, feature audit, XML grep
  docx-inspect          — inspect ZIP entries and XML inside a DOCX
  docx-fonts            — print font/style info from a DOCX
  jaccard               — compute Jaccard similarity between two PNGs or directories
  case-diff             — render and compare a fixture, print per-page scores
  graph.py              — live-updating similarity score graph over time

Testing

Tests require mutool on PATH for PDF-to-PNG rendering:

brew install mupdf        # macOS
apt install mupdf-tools   # Debian/Ubuntu

# Run all tests
cargo test -- --nocapture

# Run only Jaccard visual comparison
cargo test visual_comparison -- --nocapture

# Run only SSIM comparison
cargo test ssim_comparison -- --nocapture

Each test prints a summary table at the end:

+-------+---------+------+
| Case  | Jaccard | Pass |
+-------+---------+------+
| case1 |   44.2% | ✓    |
| case2 |   27.0% | ✓    |
| case3 |   33.5% | ✓    |
+-------+---------+------+
  threshold: 25%

Results are appended to tests/output/results.csv and tests/output/ssim_results.csv. Run python tools/graph.py to see a live-updating graph of scores over time.

Debugging Tools

Build the tools once:

cd tools && cargo build

Then run from the project root:

# Inspect XML inside a DOCX
cargo run --manifest-path tools/Cargo.toml --bin docx-inspect -- input.docx

# Print font information
cargo run --manifest-path tools/Cargo.toml --bin docx-fonts -- input.docx

# Compare two rendered pages
cargo run --manifest-path tools/Cargo.toml --bin jaccard -- a.png b.png

# Full fixture diff
cargo run --manifest-path tools/Cargo.toml --bin case-diff -- case1

Contributing

Pull requests are welcome!

Got a weird DOCX?

If you have a .docx file that produces ugly, broken, or just plain wrong output, send it to me! Real-world documents with surprising formatting are the best way to improve the converter. Open an issue or PR with the file included and I will try to make it work.

License

Apache-2.0