We at Spotify use them extensively and are actually moving away from Protobufs, which we consider as 'legacy'. The advantages of Protobufs don't make up for it

We at Spotify use them extensively and are actually moving away from Protobufs, which we consider as 'legacy'. The advantages of Protobufs don't make up for its disadvantages over plain JSON. With JSON you have universal support, simple parsing, developer and debug friendly, much easier to mock, etc etc.