# How to Handle Proprietary File Formats with MarkItDown Custom Plugins

> Learn to handle proprietary file formats with MarkItDown custom plugins. Implement the DocumentConverter interface in Python, register converters, and use the plugin entry point for automatic discovery.

- Repository: [Microsoft/markitdown](https://github.com/microsoft/markitdown)
- Tags: how-to-guide
- Published: 2026-04-11

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**Create a Python package implementing the DocumentConverter interface, register the converter via the `register_converters` hook, and expose the `markitdown.plugin` entry point in pyproject.toml to enable automatic discovery when using the `--use-plugins` flag.**

The microsoft/markitdown library provides robust conversion for common formats, but enterprise workflows often require processing proprietary or domain-specific file types. By building custom plugins that adhere to the DocumentConverter abstraction defined in [`src/markitdown/_base_converter.py`](https://github.com/microsoft/markitdown/blob/main/src/markitdown/_base_converter.py), you can extend the tool to handle any binary or text format while leveraging