Author Topic: NonVisual Desktop Access (NVDA) is an open source screen reader for Windows  (Read 2633 times)

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NonVisual Desktop Access (NVDA) is a free and open source screen reader for the Microsoft Windows operating system.

Macs have "Voice Over" built in ... But this is for Windows!

Welcome to the Home of NVDA

NonVisual Desktop Access (NVDA) is a free and open source screen reader for the Microsoft Windows operating system. Providing feedback via synthetic speech and Braille, it enables blind or vision impaired people to access computers running Windows for no more cost than a sighted person. Major features include support for over 20 languages and the ability to run entirely from a USB drive with no installation. NVDA is developed by  NV Access, with contributions from the community.

About NVDA

General Features

Providing feedback via synthetic speech and Braille, NVDA allows blind and vision impaired people to access and interact with the Windows operating system and many third party applications.

Major highlights include:

Support for popular applications including web browsers, email clients, internet chat programs and office suites
Built in speech synthesizer supporting over 20 languages
announcement of textual formatting where available such as font name and size, style and spelling errors
Automatic announcement of text under the mouse and optional audible indication of the mouse position
Support for many refreshable braille displays
Ability to run entirely from a USB stick or other portable media without the need for installation
Easy to use talking installer
Translated into many languages
Support for modern Windows Operating Systems including both 32 and 64 bit variants
Ability to run on Windows logon and other secure screens
Support for common accessibility interfaces such as Microsoft Active Accessibility, Java Access Bridge, IAccessible2 and UI Automation
support for Windows Command Prompt and console applications


It is important that people anywhere in the world, no matter what language they speak, get the same access to technologies. NVDA currently has been translated into over 20 languages including: Brazilian Portuguese, Czech, Finnish, French, German, Hungarian, Italian, Portuguese, Slovak, Spanish, Swedish, Traditional Chinese, Vietnamese, Afrikaans, Galician, Croatian, Japanese, Polish, Russian, Thai and Ukrainian.

Speech Synthesizer Support

Apart from providing its messages and interface in several languages, NVDA can also enable the user to read content in any language, as long as they have a speech synthesizer that can speak that language.

NVDA is bundled with  eSpeak, a free, open-source, multi-lingual speech synthesizer. Additionally, NVDA can use both SAPI4 and SAPI5 speech engines to provide speech output.

Innovation and Experimentation

NVDA is not driven by profit, nor is it constrained by a need to follow market trends and demands. This allows for the freedom to research, experiment with and implement new, innovative techniques to improve accessibility for blind and vision impaired users, as well as enabling features desirable to minorities to be given higher priority where appropriate.

System Requirements

NVDA runs on both 32-bit and 64-bit editions of Microsoft Windows XP or later. NVDA has no additional hardware requirements beyond those of the operating system and requires less than 50 mb of disk space.

Technical Design and Implementation

NVDA is written in the  Python programming language, which allows for rapid development among other benefits. Code that needs to be injected into other processes is written in C++ for high performance. NVDA is built with an extensible, modular, object oriented, abstract design. Its code can be easily extended in order to support new applications and controls. App Modules can be written to add overall support for a specific application, virtual buffers can be written to allow NVDA to display complex documents or other data, and NVDA Objects can be written to add support for specific controls or Windows. NVDA's abstract design allows for the seemless support and integration of many different accessibility and native APIs. It is designed with a focus on accuracy, efficiency and optimisation.

For a detailed overview of NVDA's technical design, see DesignOverview.

Licence and Copyright

NVDA is copyright ©2006-2011 NVDA contributors.

NVDA is covered by the GNU General Public License (Version 2). You are free to share or change this software in any way you like as long as it is accompanied by the license and you make all source code available to anyone who wants it. This applies to both original and modified copies of this software, plus any derivative works.


This Site was Opened on January 1st, 2007

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