Build Modern, Print-Ready PDFs with Python, Flask & WeasyPrint

PDF generation is a common requirement in modern web applications—especially for reports, invoices, purchase orders, and official documentation. One of the most powerful tools for Python developers is WeasyPrint, which allows you to convert HTML + CSS into PDFs with high-quality rendering.

This blog covers:

What is WeasyPrint?
Stylish theme ideas for PDFs
Flask API implementation
Testing the endpoint
Tips for customization

What is WeasyPrint?

WeasyPrint is a visual rendering engine for HTML and CSS that can output to PDF. It is designed to support modern CSS (like Flexbox, Grid, media queries) and is widely used for document generation.

Think of it as a "headless browser" that prints HTML/CSS to PDF with beautiful accuracy.

Why Use WeasyPrint?

Supports modern CSS (Fonts, Flexbox, Grid)
Works with templates like Jinja2
Clean API and command-line support
Supports page breaks, headers/footers, and inline images
Ideal for invoices, reports, forms, etc.

Step-by-Step Installation Commands


pip install Flask WeasyPrint
For Ubuntu:
sudo apt update
sudo apt install libpango-1.0-0 libpangocairo-1.0-0 libcairo2 libffi-dev shared-mime-info
For macOS (using Homebrew):
brew install cairo pango gdk-pixbuf libffi

Stylish Themes for PDF Design

To make PDFs not only functional but also beautiful, you can apply CSS themes just like on a webpage. Below are a few example design themes:

templates/pdf_template.html

Attractive Modern UI -


<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>{{ title }}</title>
  <link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}">
</head>
<body>
  <div class="document">

    <header class="header">
      <div class="logo">
        <h1>{{ heading }}</h1>
        <p>{{ description }}</p>
      </div>
    </header>

    <section class="info-box">
      <h2>Report Summary</h2>
      <p><strong>Date:</strong> {{ date or "June 26, 2025" }}</p>
      <p><strong>Prepared By:</strong> {{ prepared_by or "System Admin" }}</p>
    </section>

    <section class="table-section">
      <h2>Purchase Items</h2>
      <table class="styled-table">
        <thead>
          <tr>
            <th>Item</th>
            <th>Quantity</th>
            <th>Rate (INR)</th>
            <th>Total</th>
          </tr>
        </thead>
        <tbody>
          {% for item in items %}
            <tr>
              <td>{{ item.name }}</td>
              <td>{{ item.qty }}</td>
              <td>{{ item.rate }}</td>
              <td>{{ item.qty * item.rate }}</td>
            </tr>
          {% endfor %}
        </tbody>
      </table>
    </section>

    <footer class="footer">
      <p>Generated by MySystem | &copy; {{ year or "2025" }}</p>
    </footer>

  </div>
</body>
</html>

<style>
body {
  font-family: 'Segoe UI', sans-serif;
  color: #333;
  background: #f7f9fc;
  margin: 0;
  padding: 0;
}

.document {
  padding: 2rem;
  background: white;
  max-width: 800px;
  margin: auto;
  box-shadow: 0 0 20px rgba(0,0,0,0.1);
  border-radius: 10px;
}

.header {
  background-color: #4a90e2;
  color: white;
  padding: 2rem;
  border-radius: 10px 10px 0 0;
  text-align: center;
}

.header h1 {
  margin: 0;
  font-size: 2rem;
}

.info-box {
  background: #eef3f7;
  border-left: 5px solid #4a90e2;
  padding: 1rem 1.5rem;
  margin-top: 1.5rem;
  border-radius: 5px;
}

.info-box h2 {
  margin-top: 0;
  color: #4a4a4a;
}

.table-section {
  margin-top: 2rem;
}

.table-section h2 {
  border-bottom: 2px solid #ddd;
  padding-bottom: 0.5rem;
  margin-bottom: 1rem;
  color: #2c3e50;
}

.styled-table {
  width: 100%;
  border-collapse: collapse;
}

.styled-table thead {
  background-color: #e6f0ff;
  color: #333;
}

.styled-table th,
.styled-table td {
  padding: 12px 15px;
  border: 1px solid #ccc;
}

.styled-table tr:nth-child(even) {
  background-color: #f2f6fc;
}

.footer {
  margin-top: 3rem;
  text-align: center;
  font-size: 0.9rem;
  color: #999;
  border-top: 1px solid #ccc;
  padding-top: 1rem;
}
</style>

Flask + WeasyPrint PDF Generator API

Here’s how you can implement a /api/generate-pdf endpoint using Flask and WeasyPrint.

Folder Structure


project/
 │
├── app.py
├── templates/
 │   └── pdf_template.html


app.py

from flask import Flask, request, render_template, send_file, url_for
from weasyprint import HTML
import tempfile
import os

app = Flask(__name__)

@app.route("/api/generate-pdf", methods=["POST"])
def generate_pdf():
    data = request.json

    # Render HTML with data
    rendered_html = render_template("pdf_template.html",
                                    title=data.get("title", "PDF Document"),
                                    heading=data.get("heading", "PDF Generated"),
                                    description=data.get("description", ""),
                                    items=data.get("items", []))

    # Generate temporary file path
    with tempfile.NamedTemporaryFile(delete=False, suffix=".pdf") as tmp:
        pdf_path = tmp.name

    # Generate PDF
    HTML(string=rendered_html, base_url=request.base_url).write_pdf(pdf_path)

    return send_file(pdf_path, as_attachment=True, download_name="document.pdf")

Example Request (Postman or JS/Fetch)


POST /api/generate-pdf
Content-Type: application/json

{
    "title": "Monthly Purchase Report",
    "heading": "Report - June 2025",
    "description": "This report contains the list of purchases for the month of June.",
    "items": [
        { "name": "Laptop", "qty": 2, "rate": 55000 },
        { "name": "Keyboard", "qty": 5, "rate": 1200 }
    ]
}

Tips for Better PDF Styling

Use Google Fonts with @import in your CSS
Include company logos or QR codes with <img> tags and relative paths
Use media queries (@media print) to hide or show certain elements
Add page numbers using @page and counter(page)
For better print quality, always use high-resolution images


@page {
    size: A4;
    margin: 1in;
}

Common Issues & Solutions

Images not showing
Solution: Use base_url when rendering HTML (e.g., with WeasyPrint or Flask renderers)
CSS not applied
Solution: Use url_for('static', filename='path/to/file.css') in templates
Broken fonts
Solution: Use system fonts (like Arial, Times) or host fonts locally (avoid external CDNs)
Header/Footer not repeating on every page
Solution: Use position: running(header) in CSS and define headers/footers using @page rules

Conclusion

With WeasyPrint and Flask, you can create stylish, responsive, and professional PDF documents just like a web page. Thanks to its HTML + CSS-based design, your frontend team can collaborate with backend developers to make the perfect document experience.

About Author

Saurav Jaiswal