Best pratice uploading, retrieving photos,videos Android/ios mobile app

i am in the process to develop a new website that will let the user to post news, articles, images and videos on the website arraged by categories (sports, finance etc….).

my question: where is the best solution recommended to store videos, images and audio, taking into consideration that the other users that maybe interested in this category will be able to see the videos or images on their own wall.

thank you.