Markdown to PDF, pure Python, zero dependencies. MIT-licensed. Deterministic.
pip install inkmd
inkmd in.md -o out.pdfThat's the whole install. No system packages, no fonts to install, no Chrome binary, no apt-get. Works the same on macOS, Linux, Windows, Alpine, AWS Lambda, a locked-down CI runner, or a Steam Deck.
examples/hero-sample.md rendered through inkmd: headings, inline styles, strikethrough, blockquote, GFM table, list, fenced code, autolinked URL and email all in one page.
See also examples/inkmd-brief.md, a two-page project brief written in inkmd-renderable markdown.
- A single pure-Python wheel. No native extensions, no system libraries. Installs in under a second.
- Faithful CommonMark plus the parts of GFM people actually use: tables, autolinks, strikethrough, fenced code with language tags. The supported features section has the full matrix.
- PDFs that look right. Real AFM-driven kerning emitted via TJ arrays, clickable links, tinted code-block backgrounds, blockquote rules that stack for nested quotes, table alignment, headings that breathe.
- Byte-identical output for the same input. No clocks, no random IDs. Useful for version control, signed PDFs, audit trails, reproducible CI.
- Two layers of API: a CLI and a
compile()/render_file()library function. The whole public surface is two functions.
Measured against WeasyPrint + markdown (the closest pure-Python alternative) on the same input documents, on the same machine. Methodology and full caveats in BENCHMARKS.md; the script is at scripts/bench.py and is reproducible.
| Metric | inkmd | WeasyPrint | Ratio |
|---|---|---|---|
| Install size (venv) | 10.5 MB | 74.6 MB | 7.1x smaller |
| Cold-start render, ~1 page | 132 ms | 814 ms | 6.2x faster |
| Cold-start render, ~11 pages | 174 ms | 1.40 s | 8.0x faster |
| Peak RSS, ~11 pages | 19 MB | 122 MB | 6.4x lower |
WeasyPrint produces slightly smaller PDFs for documents over a few pages (it compresses content streams; inkmd does not). WeasyPrint also supports full Unicode, page-splitting tables, and CSS, which inkmd does not. inkmd does support images as of v0.2 (PNG and JPEG embedding). The right tool depends on your input and your environment — the comparisons doc has the full picture.
Markdown to PDF is a solved problem in theory and a minefield in practice. Every other tool brings heavy system dependencies that don't survive the trip into an Alpine container, a Lambda function, or a Windows machine without admin rights.
| Tool | What goes wrong |
|---|---|
| wkhtmltopdf | Deprecated since 2023. Unpatched CVEs. |
| Chrome headless / Puppeteer | 200MB+ install. 5 to 15s cold-start latency. |
| WeasyPrint | Needs Pango, cairo, GObject (350 to 550MB of system packages). Breaks on Alpine and Windows. |
| Pandoc + LaTeX | 3GB texlive install. |
| PyMuPDF-based tools | Don't build on Alpine musl. |
borb |
AGPL, so unusable in closed-source or commercial projects without a paid licence. |
inkmd runs anywhere Python runs. It's the markdown-to-PDF compiler you'd write yourself with a free weekend if you didn't want to take a dependency on a browser.
For the longer, honest version of how inkmd compares against every realistic alternative (including where inkmd is worse), see docs/comparisons.md.
- CI documentation pipelines. Compile READMEs, release notes, or changelogs to PDF as a build artefact, in a stripped-down container, without
apt-get. - Agent-generated documents. LLM agents that need to deliver a PDF (CVs, reports, summaries) can call
inkmd.compile()directly. No subprocess, no shell-out, no Chrome. - Reproducible audit trails. Hash the markdown, hash the PDF, and the same input gives the same output bytes. Useful for compliance, signed reports, version-controlled docs.
- Serverless rendering. Lambda plus zero system dependencies equals a PDF endpoint that cold-starts in well under a second.
- Restricted environments. Locked-down CI runners, embedded hardware, anywhere installing a 200MB browser isn't an option.
v0.2, MIT-licensed. 649 tests across 28 files. Stdlib-only, Python 3.9+. Byte-deterministic output.
Conformance against the public spec suites: CommonMark 0.31.2 at 554/652 (85.0%); GFM extensions at 20/28 (71.4%). The full per-section breakdown, the v0.3-tier and v0.4-tier classification of remaining failures, and the real-world-impact framing are in docs/conformance.md. Threat model in docs/security.md. Edge-case render samples committed as PDFs in docs/gallery/.
The v0.2 design principle is utter consistency: for any markdown construct the CommonMark spec has a clear answer about, inkmd follows that answer. The conformance percentage is a proxy for "what GitHub showed you is what you get" — it isn't the goal in itself.
From PyPI:
pip install inkmdOr grab the single-file zipapp (no pip install required). Each tagged release attaches an inkmd.pyz of around 300 KB that you can drop anywhere Python 3.9+ is available:
curl -L -o inkmd.pyz https://github.com/eagredev/inkmd/releases/latest/download/inkmd.pyz
python inkmd.pyz in.md -o out.pdfOr build it yourself from a checkout:
python scripts/build_zipapp.py # produces dist/inkmd.pyzinkmd in.md -o out.pdf # file in, file out
inkmd in.md > out.pdf # file in, stdout out
inkmd < in.md > out.pdf # stdin in, stdout out
inkmd in.md -o out.pdf --page-size A4 --family times
inkmd in.md -o out.pdf --no-autolinks --no-html
inkmd in.md -o out.pdf --allow-remote-images # fetch http(s) image URLs
inkmd in.md -o out.pdf --allow-unsafe-urls # disable URL scheme filter
inkmd --versionimport inkmd
# Compile markdown text to PDF bytes
pdf_bytes = inkmd.compile(md_text)
# Or convert files directly
inkmd.render_file("in.md", "out.pdf")
# Options (same on both functions)
pdf_bytes = inkmd.compile(
md_text,
page_size="A4", # or "letter" (default)
family="times", # or "helvetica" (default)
autolinks=False, # opt out of GFM bare-URL/email detection
safe=True, # URL scheme allow-list (default True)
html=True, # inline HTML allow-list (default True)
allow_remote_images=False, # explicit opt-in to fetch http(s) images
)The public API is intentionally narrow: two functions, no classes to instantiate, no state to manage. The CLI is a thin argparse wrapper around compile().
| Feature | inkmd |
|---|---|
| Paragraphs with line wrapping | Yes |
ATX headings (# to ######) |
Yes |
Setext headings (=== / ---) |
Yes |
Ordered lists, arbitrary start |
Yes |
Unordered lists (- / * / +) |
Yes |
| Nested lists, mixed marker types | Yes |
| Tight vs. loose list detection | Yes |
| Blockquotes | Yes |
| Nested and multi-paragraph blockquotes | Yes |
| Blockquotes wrapping any block type | Yes |
| Blockquote lazy continuation | Yes |
| Fenced code blocks | Yes |
| Code block language tag (info string) | Yes |
| Indented code blocks | Yes |
| Indented code blocks inside list items | Yes |
| Tabs preserved verbatim inside code | Yes |
Code spans (`code`, multi-backtick) |
Yes |
Emphasis (*, _) |
Yes |
Strong emphasis (**, __) |
Yes |
Triple *** becomes nested italic-bold |
Yes |
| Rule of 3 plus intraword-underscore | Yes |
| Backslash escapes | Yes |
| Thematic breaks | Yes |
Inline links [text](url) |
Yes |
Inline link titles ("...", '...', (...)) |
Yes |
Angle-bracket autolinks <url> |
Yes |
Reference links ([t][ref], [ref][], [ref]) |
Yes |
Reference link definitions ([ref]: url "title") |
Yes |
| Hard line breaks (two-space or backslash form) | Yes |
| Soft line breaks | Yes |
HTML5 entity references (&, *) |
Yes |
Images  |
Yes |
Reference-style images ![alt][ref] |
Yes |
Image-inside-link [](/repo) |
Yes |
Inline HTML allow-list (<sub>, <mark>, <u>, <kbd>, <br>) |
Yes |
| Block-level raw HTML | v0.3 |
| Feature | inkmd |
|---|---|
| Pipe tables | Yes |
| Table column alignments | Yes |
Bare URL autolinks (https://..., www....) |
Yes |
Bare host autolinks (host.tld/path) |
Yes |
Email autolinks (<addr@host>) |
Yes |
| Bare email autolinks (no angle brackets) | v0.3 |
Bare mailto: / xmpp: schemes |
v0.3 |
Strikethrough ~~text~~ / ~text~ |
Yes |
Task lists - [ ] / - [x] |
Yes |
| Disallowed-HTML filter | curated subset |
- Clickable PDF
/Linkannotations on every URL, inline links and autolinks alike. - Blue underlined link text.
- Light-grey background tint behind fenced code blocks.
- Thin grey vertical rules for blockquotes. Stacked side-by-side for nested quotes.
- Tinted table headers with full grid borders and per-column alignment.
- AFM-correct kerning emitted via TJ arrays (Helvetica and Times both fully kerned).
- Strikethrough drawn as a thin horizontal bar at glyph mid-height.
- Helvetica family (default) or Times family. Code uses Courier.
- Standard PDF letter and A4 page sizes.
- WinAnsi character encoding: em-dash, en-dash, curly quotes, ellipsis, most Western European glyphs.
- Codepoints outside WinAnsi (CJK, Cyrillic, emoji, most non-Latin scripts) render as
?in v0.1. v0.2 lifts this with font embedding.
inkmd produces byte-identical PDF output for the same markdown input on every platform, every Python version, every run. No real-time clocks, no random IDs, no platform-dependent iteration order.
If you hash the markdown and the PDF, the relationship is stable forever. Useful for version-controlled documents, signed/hashed PDFs, reproducible CI builds, and audit trails.
| Feature | When | Why |
|---|---|---|
| TTF / OTF font embedding | v0.3 | v0.2 uses PDF's 14 base fonts. Tiny output, no font files to ship, but limits codepoints to WinAnsi |
Block-level raw HTML (<table>...</table> etc.) |
v0.3 | inkmd v0.2 covers inline HTML via the safe allow-list; block-level passthrough is queued |
| Headers, footers, page numbers | v0.3 | Needs a per-page chrome system |
| Page-splitting for oversized tables | v0.3 | Tables currently place atomically and overflow if taller than a page |
| Tables inside blockquotes | v0.3 | Table detection runs at document level only |
| Blockquote inside a list item | v0.3 | > inside an item renders as paragraph text in v0.2; per-item blockquote state coming |
| RGBA / indexed PNG embedding | v0.3 | v0.2 supports RGB and grayscale PNG; common screen-grab RGBA needs the alpha-channel pipeline |
| GIF image support | v0.3 | LZW decoder + palette resolution |
| Tagged PDF / PDF/UA accessibility | v1.0+ | Under consideration |
| PDF/A archival format | n/a | Not planned |
| Math (LaTeX-style) | n/a | Out of scope. Use Pandoc + LaTeX. |
| Themes / CSS | n/a | Out of scope. Markdown's value is its constraints. |
Four layers, each strictly above the previous:
parseris a single-pass container-aware block parser plus a CommonMark inline tokeniser. Produces a frozen-dataclass AST.renderlowers AST blocks toRenderedBlockrecords with runs, spacing, indent, decorations. Carries font and link state through inline nesting.layoutwraps runs into pages, positions eachPositionedRunagainst the page coordinate system, emits background rectangles for code blocks, vertical rules for blockquotes, underline plus annotation pairs for links, and bars for strikethrough.pdfserialises pages into PDF bytes. Text viaTj/TJ-with-kerning, graphics viarg/re/f, link annotations via per-page/Annotsarrays.
No layer imports a higher one. The whole pipeline is around 3,500 lines of pure-Python logic plus 4,700 lines of generated AFM kerning tables. That's it. For a deeper walk-through (the emphasis algorithm, AFM kerning, determinism mechanics), see docs/internals.md. The complexity profile is in LIZARD-AUDIT.md.
A note on font rendering in v0.1
inkmd v0.1 uses PDF's 14 base fonts (Helvetica, Times, Courier, Symbol, ZapfDingbats and their variants). These are spec-mandated to be available in every conforming PDF reader, so we don't ship any font files. The output stays tiny and dependency-free.
The trade-off is that the actual rendering depends on which Helvetica (or Times, etc.) the reader's system provides:
- macOS ships Helvetica Neue (real Helvetica). Renders as designed.
- Windows with Adobe Reader ships real Helvetica. Renders as designed.
- Linux typically substitutes Nimbus Sans (URW++'s free Helvetica clone). Renders very similarly but with slightly different side bearings, so spacing between glyphs can look subtly different.
- Mobile (iOS / Android) ships system Helvetica or Roboto variants. Mostly fine.
The advance widths are correct everywhere (PDF readers honour the AFM-published metrics), so layout (page breaks, line wrapping, paragraph flow) is identical across systems. What varies is the precise glyph shape within each advance-width box, which can produce slightly different visual spacing.
For most use cases this is fine. If you need pixel-identical rendering across every system (signed or archival documents, for example), wait for v0.2 font embedding, which will bundle font outlines inside each PDF.
The release tiers are about what a real user sees, not about chasing a percentage.
- v0.1 — Proof of concept: working basic PDFs. Shipped.
- v0.2 — Most sane use cases work; remaining failures are rare and defensible. Shipped. CommonMark 85%, GFM extensions 71%. Adds reference links, images (PNG + JPEG), task lists, inline HTML allow-list, hard line breaks, indented code blocks (including inside list items), URL scheme filter, tab preservation, image-inside-link.
- v0.3 — Visually identical for the user even where spec tests still fail. Adds block-level raw HTML pass-through, blockquote-inside-list, headers/footers/page numbers, page-splitting for oversized tables, TTF font embedding (full Unicode), RGBA/indexed PNG, GIF.
- v0.4 — 100% CommonMark and 100% GFM extensions. The long-tail spec-corner cases.
- v1.0 and beyond — Tagged PDF, accessibility, TOC generation, cross-references. PDF/A and similar under consideration.
MIT. See LICENSE.
The 14 standard PDF fonts and their AFM metric files are public-domain artefacts published by Adobe (adobe-type-tools/Core14_AFMs). PDF format reference: ISO 32000-1.
Built by Dylan Moir. If inkmd saves you a fight with WeasyPrint or a 200MB Chrome install in your CI, a star on the repo is plenty.