How to make a download repository like http://bit.ly/2Mpo3X9 or http://bit.ly/2iuTMpZ?

I've seen these ROM Download repositories like Pixel Experience and Lineage OS: https://download.lineageos.org https://download.pixelexperience.org/

I have been trying to do the same. So far, I have made the UI, everything's in place except for the downloads. The websites seem to have separate pages for every device. Each page has a table which takes some information from a json file. How can I create such webpage? I know how to read a json but how to create separate pages for each device and show the json in a table?