A free program for Android, by Stupendous Andro.

Json File Opener & Viewer is an application that allws you to edit your Json files. It also allows you to modify the file at your convenience. You can also open the file whenever you like, you can easily copy the content of the file, share to your chosen recipients, convert the file to PDF, and other features for you to explore and discover. 

Moreover, Json File Opener & Viewer is created for free for you to prevent yourself in accessing sites that has the same feature with a fee.