I want to build an application that will enable a user to convert files from any one of three formats, into any of those three formats. In order words, there are three formats:
aaa, bbb and ccc
My application will enable the user to convert aaa to ccc, or bbb to aaa, or ccc to bbb, etc. The origins of the three formats are:
aaa (closed source product, I have permission and a license to read/write this format)
bbb (open source GPL license, file format is published on the Internet)
ccc (open source GPL license, file format is visible as JSON and easy to read)
All source code will be my original code, I will not be using any source code from any open source product.
The question is: Given that I am reading file formats created by GPL products, do I need to release my source code? This will be difficult given that I am also reading a properietary format. Ultimately I wish to sell a binary and not release any source given the complexity around the one closed source format.