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Liblouis is an open-source braille translator and back-translator named in honor of Louis Braille. It features support for computer and literary braille, supports contracted and uncontracted translation for many languages and has support for hyphenation. New languages can easily be added through tables that support a rule- or dictionary based approach. Tools for testing and debugging tables are also included. Liblouis also supports math braille (Nemeth and Marburg).

Liblouis has features to support screen-reading programs. This has led to its use in two open-source screenreaders, NVDA and Orca. It is also used in some commercial assistive technology applications for example by ViewPlus.

Liblouis is based on the translation routines in the BRLTTY screenreader for Linux. It has, however, gone far beyond these routines. In Linux and Mac OSX it is a shared library, and in Windows it is a DLL.

Liblouis is free software licensed under the GNU LGPLv2.1+ (see the file COPYING.LESSER).

The command line tools, are licensed under the GNU GPLv3+ (see the file COPYING).


For documentation, see the liblouis documentation (either as info file, html, txt or pdf) in the doc directory. For examples of translation tables, see en-us-g2.ctb, en-us-g1.ctb, chardefs.cti, and whatever other files they may include in the tables directory. This directory contains tables for many languages. The Nemeth files will only work with the sister library liblouisutdml.


After unpacking the distribution tarball from releases go to the directory it creates. You now have the choice to compile liblouis for either 16- or 32-bit unicode. By default it is compiled for the former. To get 32-bit Unicode run configure with --enable-ucs4.

After running ./configure run make and then sudo make install. As a final step you might have to run sudo ldconfig. For other ways of installation, see the file HACKING.

This will produce the liblouis library and the programs lou_allround (for testing the library), lou_checkhyphens, lou_checktable (for checking translation tables), lou_debug (for debugging translation tables), lou_translate (for extensive testing of forward and backwards translation) and lou_trace (for tracing if individual translations). For more details see the liblouis documentation.

If you wish to have man pages for the programs you might want to install help2man before running configure.

If you want to run the test suite with make check you should install libyaml as that will enable extensive tests on the tables. If you want to skip those tests you can do so by running configure --without-yaml.


You can contribute to Liblouis in several different ways:

  • If you have comments, questions, or want to use your knowledge to help others, come join the conversation on either the mailing list or on IRC. You can reach us at or in channel #liblouis on
  • To report a problem or request a feature, please file an issue.
  • Of course, we welcome pull requests and patches.

Finally, if you want to see what we have for the future and learn more about our release cycles, all this information is detailed on the wiki

Release Notes

For notes on the newest and older releases see the file NEWS.


Liblouis was begun in 2002 largely as a business decision by ViewPlus. They believed that they could never have good braille except as part of an open source effort and knew that John Boyer was dying to start just such a project. So ViewPlus did start it on the agreement that they would give a small monthly stipend to John Boyer that allowed him to pay for sighted assistants. While ViewPlus has not contributed much to the coding, it certainly has contributed and continues to contribute to liblouis through that support of John Boyer.