For centuries, Swahili was written in Arabic script, and hundreds of manuscripts in collections around the world testify to its long tradition of written literature. Over the last century, however, Swahili in Roman script has become the norm.
Andika! (meaning Write! in Swahili) is a set of tools to make Swahili in Arabic script as easy to use as Swahili in Roman script - it is equally easy to read and write the the language in either script. The tools provide a consistent, standardised transliteration of Swahili in Arabic script, and a one-to-one mapping of this to Swahili in Roman script, so that you can convert from one to the other.
More details, along with extensive examples of Andika! output, are on the website, or in the manual in the docs folder (which also contains detailed information about installing and using the offline tools to handle manuscripts). Since the manual is currently over 100 pages long, it is best to download the pdf rather than try to read it in the GitHub interface.