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What are NVDA Add-ons?

Add-ons allow you to customize and extend NVDA’s functionality. They can:
  • Add support for specific applications (App Modules)
  • Implement new global commands (Global Plugins)
  • Customize behavior of controls (NVDA Objects)
  • Add speech synthesizers and braille display drivers
  • Provide new functionality across the entire operating system
Add-ons are Python modules packaged with a manifest file and distributed as .nvda-addon files.

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Types of Add-on Components

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App Modules

App modules provide application-specific support. They:
  • Are loaded when a specific application is running
  • Are named after the executable (e.g., notepad.py for notepad.exe)
  • Can handle events and define scripts specific to that application
  • Are automatically loaded and unloaded as the application starts and closes
Learn more about App Modules →

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Global Plugins

Global plugins provide functionality across all applications. They:
  • Are loaded when NVDA starts
  • Can respond to events from any application
  • Can implement global commands accessible anywhere
  • Remain active until NVDA exits
Learn more about Global Plugins →

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Custom NVDA Objects

NVDA Objects represent individual controls and widgets. You can create custom NVDA Object classes to:
  • Provide better accessibility for specific controls
  • Customize how information is presented to users
  • Add functionality to existing controls
  • Implement text support for controls that don’t natively support it
Learn more about Custom NVDA Objects →

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Add-on Structure

myAddon/
├── manifest.ini
├── appModules/
│   └── myapp.py
├── globalPlugins/
│   └── myplugin.py
├── locale/
│   ├── en/
│   └── es/
└── doc/
    └── en/
        └── readme.md

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Development Workflow

1

Set up the scratchpad directory

Enable the scratchpad directory in NVDA Settings > Advanced. This allows you to test code without creating full add-on packages.The scratchpad is located at: %APPDATA%\nvda\scratchpad\
2

Create your code

Place your Python files in the appropriate subdirectories:
  • scratchpad/appModules/ for app modules
  • scratchpad/globalPlugins/ for global plugins
3

Reload plugins

Use NVDA+Control+F3 or select Tools > Reload plugins to test your changes without restarting NVDA.
4

Package as an add-on

Once your code is working, create a proper add-on package with a manifest file for distribution.

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API Stability

The NVDA Add-on API consists of all NVDA Python objects, classes, and functions, excluding:
  • Symbols prefixed with underscore (_) - these are private
  • Transitive imports
  • Pip packages (may be updated at any time)
Breaking changes only occur in annual .1 releases (e.g., 2026.1). Standard releases (2026.2, 2026.3) preserve API signatures but may add new features.

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API Release Cycle

  • Annual API-breaking release (e.g., 2026.1): Signature-breaking changes are permitted
  • Standard releases (e.g., 2026.2, 2026.3): Existing API signatures are preserved, new features may be added
  • Bug fixes and behavioral refinements: Permitted in any release
  • Security improvements: Take precedence over backward compatibility

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Key Resources

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Python Requirements

NVDA add-ons are written in Python. You should be familiar with:
  • Python syntax and basic concepts
  • Object-oriented programming
  • Python modules and packages
  • Event-driven programming
NVDA uses a specific version of Python. Check the Developer Guide for the current version.

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Next Steps

Create an App Module

Add application-specific functionality

Build a Global Plugin

Implement system-wide features

API Reference

Browse the complete API documentation

Distribution Guide

Package and distribute your add-on

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