Why Code Blocks Are the Hardest Part of Markdown to PDF Conversion
If you've ever tried to convert a Markdown file with code blocks into a PDF, you've almost certainly run into at least one of these problems:
- Monospace font not used — code renders in the same proportional font as body text
- No syntax highlighting — everything is plain black text
- Lines overflow the page and get cut off
- Indentation is lost, making code unreadable
- Background color disappears, so code blocks look identical to normal paragraphs
These aren't random bugs. They happen because most tools take a shortcut: they parse Markdown into HTML, then dump it into a PDF renderer that ignores CSS entirely. Code blocks depend heavily on CSS (font-family: monospace, white-space: pre, overflow-x: auto, background colors) — and when CSS is stripped out, code becomes unreadable.
What Broken Code Blocks Look Like
Here's a concrete example. Take this simple JavaScript function in a Markdown file:
```javascript
async function fetchUser(id) {
const response = await fetch(`/api/users/${id}`);
if (!response.ok) throw new Error("User not found");
return response.json();
}
```
A broken PDF converter will output something like this in the PDF:
async function fetchUser(id) { const response = await fetch("/api/users/" + id); if (!response.ok) throw new Error("User not found"); return response.json(); }
No line breaks. No monospace. No background. Just a wall of text that's impossible to read.
A correct PDF converter preserves:
- The monospace font (
Courier,Fira Code, or similar) - Each line on its own line with proper indentation
- A light gray or dark background that visually separates code from prose
- Syntax-colored tokens (keywords, strings, functions) if it supports highlighting
The Real Code Example
Here's the full JavaScript snippet we'll use to test PDF output throughout this guide:
// DevMark API example — fetch and convert Markdown to PDF
async function convertMarkdownToPDF(markdownContent) {
// Parse Markdown into an HTML string
const { marked } = await import("marked");
const htmlContent = marked.parse(markdownContent);
// Wrap in a styled document for proper PDF rendering
const styledHTML = `
<!DOCTYPE html>
<html>
<head>
<style>
body { font-family: Georgia, serif; line-height: 1.6; }
pre { background: #f4f4f4; padding: 1rem; border-radius: 4px; overflow-x: auto; }
code { font-family: 'Courier New', monospace; font-size: 0.9em; }
</style>
</head>
<body>${htmlContent}</body>
</html>
`;
// Use html2pdf.js (browser only — never run server-side)
const html2pdf = (await import("html2pdf.js")).default;
return html2pdf()
.set({ margin: 10, filename: "output.pdf", html2canvas: { scale: 2 } })
.from(styledHTML)
.save();
}
Notice the three things that make this work: the <pre> element gets a background and padding, code gets a monospace font, and html2pdf.js is imported dynamically so it only ever runs in the browser — never on the server where window is undefined.
Step-by-Step: Convert Markdown with Code Blocks to PDF
Step 1 — Paste Your Markdown
Open the converter below (or at /markdown-to-pdf) and paste your Markdown. Your code blocks should be fenced with triple backticks and include a language identifier:
```javascript
// your code here
```
Language identifiers like javascript, python, bash, typescript, and json enable syntax highlighting. Without one, the converter still preserves formatting — but coloring is skipped.
Step 2 — Check the Live Preview
The preview panel renders your Markdown in real time. Before downloading, verify that:
- Code blocks have a distinct background
- Indentation is preserved (4-space indents should look like 4 spaces, not 1)
- Long lines wrap correctly or have a horizontal scrollbar hint
If the preview looks right, the PDF will match — the converter uses the same rendered HTML for both.
Step 3 — Choose a Theme (Optional)
Light themes (GitHub, Default) work best for printed PDFs because they use dark text on a white or light-gray code background — exactly what you'd expect on paper. Dark themes look great on screen but can waste toner and reduce readability when physically printed.
Step 4 — Download the PDF
Click Download PDF. The conversion happens entirely in your browser using html2pdf.js — your Markdown never leaves your machine, and no server processes it.
Tip: For technical documentation, use the GitHub theme. It matches the code block style developers already recognize from GitHub READMEs.
Try It Right Here
You can convert Markdown with code blocks to PDF directly below — no signup required:
Common Problems and Fixes
Problem: Code lines are cut off at the right edge of the page Fix: Make sure your code lines are under ~80–90 characters. The converter wraps very long lines, but it can't reformat code logic. Break long lines manually before converting.
Problem: Syntax highlighting doesn't appear
Fix: Add a language tag after the opening triple backtick. ```js instead of just ```.
Problem: Indentation collapses to a single space Fix: Use spaces, not tabs. Some PDF renderers collapse tab characters. Replace tabs with 2 or 4 spaces.
Problem: Code block background is white/invisible in the PDF Fix: Use a theme other than "Minimal." The Minimal theme intentionally strips backgrounds for cleaner prose documents. Switch to GitHub or Default.
How DevMark Handles Code Blocks Differently
Most online Markdown-to-PDF converters run on the server: they accept your Markdown, process it with a headless browser or a PDF library, and return a file. The problem is CSS support in these pipelines is inconsistent — especially for code blocks.
DevMark takes a different approach. The entire conversion runs client-side in your browser using html2pdf.js with html2canvas. This means:
- Full CSS fidelity — the PDF is a snapshot of what you actually see in the preview
- No data sent to a server — your code stays on your machine
- Consistent output — what you see is exactly what you get
This is especially important for code blocks, which rely on CSS properties (white-space: pre, font-family: monospace, background-color) that server-side PDF generators often discard.
For GitHub READMEs specifically, check out our guide on converting GitHub READMEs to PDF — it covers badge handling and image-heavy READMEs alongside code blocks.
Frequently Asked Questions
Q: Does DevMark support syntax highlighting for all programming languages?
It supports the most common ones: JavaScript, TypeScript, Python, Bash, JSON, HTML, CSS, SQL, Go, Rust, and more. The underlying parser uses marked with highlight.js for token coloring. If your language isn't highlighted, formatting (monospace font, background, indentation) is still preserved — only color tokens are skipped.
Q: Will the code block look the same in the PDF as in the preview?
Yes. The PDF is generated from the same rendered HTML you see in the preview panel. There's no second render step that could lose styles.
Q: Can I convert a file with hundreds of lines of code?
Yes, with a caveat: very long files (10,000+ lines) can slow down the browser-side conversion because html2canvas captures the entire rendered page as an image. For large files, consider splitting them into sections or reducing the canvas scale in the settings.
Q: My code has backticks inside the code block. How do I escape them?
Use four backticks to open and close the fenced block instead of three. This allows triple backticks inside the block without escaping.
Q: Is there a file size limit?
There's no server-side limit because conversion happens in your browser. The practical limit is your device's RAM — most modern machines handle Markdown files up to several megabytes without issue.
Q: Can I use DevMark for confidential code?
Yes. Because conversion is entirely client-side, your code is never transmitted to any server. You can use it for proprietary or sensitive code with confidence.
Ready to convert? Head to the Markdown to PDF converter and paste your code-heavy Markdown — your code blocks will render exactly as intended.