If you are generating HTML reports, invoices, or portal pages and you need PDFs in bulk, the key requirement is repeatable output across machines. This step-by-step guide shows how to batch convert multiple HTML files to PDF in Python using Aspose.HTML for Python via .NET. You will build a folder-based converter, then extend it to SVG-heavy pages and embedded fonts for consistent rendering.

Why Use Aspose.HTML for HTML to PDF Batch Conversion?

Aspose.HTML for .NET is a document rendering API that can load HTML content from files or URLs and export to PDF with fine control over rendering options. For batch conversion scenarios, the key benefits are

  • Reliable rendering without browser automation
  • Control over PDF options such as page size, margins, and background rendering
  • Predictable execution in server environments
  • Ability to standardize fonts and resources across many conversions

Batch Convert Multiple HTML Files to PDF in Python — Step by Step

Step 1: Set Up Your Environment

You need Python and a .NET runtime that matches your deployment environment. If you plan to run conversions on a server, install the same runtime there as well.

Install Aspose.HTML for Python via .NET

Run:

pip install aspose-html-net

If you use a virtual environment:

python -m venv .venv
.venv\Scripts\activate
pip install aspose-html-net

Step 2: Create Input and Output Folders (Optional)

Create two folders in your project directory:

  • input_html for HTML files and assets
  • output_pdf for generated PDFs

Recommended structure for reliable asset resolution:

  • input_html

    • report1.html

    • report2.html

    • styles

      • site.css

    • images

      • logo.png

    • fonts

      • Inter Regular.ttf

Keep CSS, images, and fonts inside the same root so relative paths work consistently.

Step 3: Write the Batch Conversion Script

This script scans the input folder, finds .html and .htm files, and converts each file into a PDF with the same relative path under the output folder. It also logs success and failure per file.

Code example: Batch convert a folder of HTML files to PDF.

This section implements the primary batch pattern used in enterprise automation. It enumerates HTML files, builds deterministic output paths, converts each document, and returns a summary report you can store for monitoring and reruns.

Follow the steps below:

  1. Set input and output folders.
  2. Enumerate all HTML files.
  3. Load each HTML document.
  4. Convert each document to PDF.
  5. Save PDFs with deterministic names.

This code example demonstrates how to convert a collection of HTML files to PDF using Aspose.HTML for Python via .NET.

Note: This code example demonstrates the core functionality. Before using it in your project, make sure to update the file paths (input, output, etc.) to match your actual file locations, verify that all required dependencies are properly installed, and test thoroughly in your development environment. If you encounter any issues, please refer to the documentation or reach out to the support team for assistance.

Step 4: Run the converter and verify output

Run:

python batch_html_to_pdf.py

Verify:

  • PDFs are created under output
  • Folder structure mirrors input
  • Layout matches expectations
  • CSS and images appear correctly

If CSS is missing, jump to the Fix Missing CSS, Images, and Broken Relative Paths section because it is almost always a path or asset packaging issue.

Make Font Rendering Consistent by Embedding Fonts

If you are generating invoices or compliance documents, font substitution can change line breaks and pagination. The most reliable solution is to ship fonts with your templates and load them using CSS.

Code example: Convert HTML to PDF with embedded fonts

This section focuses on template packaging. The conversion code stays the same. You embed fonts by using CSS @font-face with relative paths.

Follow the steps below:

  1. Place required fonts in an accessible folder.
  2. Reference fonts via CSS using font-face rules.
  3. Ensure the HTML loads the CSS and fonts via relative paths.
  4. Convert HTML to PDF and verify font appearance.

Folder structure:

  • input_html

    • invoice.html

    • styles

      • invoice.css

    • fonts

      • Inter Regular.ttf
      • Inter Bold.ttf

CSS sample:

@font-face {
  font-family: "Inter";
  src: url("../fonts/Inter Regular.ttf") format("truetype");
  font-weight: 400;
  font-style: normal;
}

@font-face {
  font-family: "Inter";
  src: url("../fonts/Inter Bold.ttf") format("truetype");
  font-weight: 700;
  font-style: normal;
}

body {
  font-family: "Inter", Arial, sans-serif;
}

Run your batch script again and verify:

  • The PDF uses the intended font.
  • Spacing and pagination match your expected layout.

Fix Missing CSS, Images, and Broken Relative Paths

If your PDF output looks unstyled or images are missing, use this checklist:

  1. Confirm all asset references in HTML are relative to the HTML file location.
  2. Keep templates and assets under one root folder, such as input.
  3. Avoid absolute paths that only exist on your machine.
  4. Avoid assets served by URLs that the server cannot access.

A quick test is to open the HTML file locally and confirm it loads CSS and images from the same folder structure you ship to production.

Conclusion

You now have a complete step-by-step approach to batch convert multiple HTML files to PDF with Aspose.HTML in Python via .NET. Automating the batch conversion of multiple HTML files to PDF streamlines document generation for enterprise systems. By installing the SDK, preparing a clear list of sources, configuring PDF options for embedded fonts and SVG preservation, and handling errors gracefully, you can build a reliable conversion pipeline that scales to thousands of pages. The SDK’s progress events and rich API make it easy to monitor long‑running jobs and ensure consistent output quality.

For production use, you can purchase a license by visiting the pricing page. Alternatively, you can request a temporary license for evaluation purposes. Explore more tutorials on the Aspose.HTML blog and join the community on the forums for additional support.

FAQs

1. Can I batch convert both HTML and HTM files in one run?

Yes. In your batch script, include both .html and .htm extensions when scanning the input folder, then convert each file to a PDF and keep the same relative output structure.

2. Why is my PDF missing CSS styling or images?

This usually happens when relative paths do not resolve in the conversion environment. Keep CSS, images, and fonts under the same input root, use relative paths in HTML and CSS, and avoid machine-specific absolute paths.

3. How do I make PDF output consistent across servers?

Bundle required fonts with your templates and reference them using CSS font face rules. Also keep all assets local and versioned so the converter always sees the same HTML, CSS, images, and fonts in every environment.

4. Does Aspose.HTML preserve SVG quality in the generated PDF?

Yes. Inline SVG elements generally render as vector content in PDF. After conversion, zoom in on charts and icons to confirm edges remain sharp and that text inside SVG uses the expected fonts.

5. How do I handle failures when converting hundreds or thousands of files?

Process files independently, catch exceptions per file, and write a summary report that lists succeeded and failed items. This lets you rerun only the failed files instead of repeating the entire batch.

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