You could have downloaded Grantha 1.0 from our software library for free. The most popular version of the software is 1.0. The common filename for the program's installer is Grantha.exe. The software is included in Desktop Tools. The actual developer of the free program is Virtual Vinodh.
From the developer:
There are around 5 fonts for Grantha: e-Grantamil,Code2000, IIT-M Grantha Font, Ganapathy & Kunchitapada. Out of those 3 are Truetype, 1 is Opentype, and 1 is encoded in PUA.
Ganapathy & Kunchitapada fonts are very early fonts created around 1998, so they are not exactly very aesthetic in appearance. Both have the same Layout, therefore text composed in one font can be switched to the other without any loss.
You may want to check out more software, such as Search Gurbani or iSearchGurbani, which might be similar to Grantha.