It is recommended that you output your data as files so that storage on the server would be simpler.
You may decide the format for the files as per your requirements such as industry standard SAM/BAM/VCF etc. or in generic form such as text files. However you may pass the data in JSON format from the APIs since it is a requirement for our custom display modules to display data.
The Sequencing.com site can also display your app results as HTML/HTML5, PDFs, tables, graphs, images and video.