I have been using MongoDB lately for logging the results of my computational experiments, and I have found that it is a pretty fun piece of software to use. Since MongoDB is designed to store large amounts of data across a distributed network, It seems like it could be a good match for zarr. I went ahead and made a very simple MutableMapping wrapper to MongoDB: https://gist.github.com/nbren12/9842cf22f173a864a7c8377c01ad06c5, and I am wondering if this is something that might be worth cleaning up and adding to zarr.

It would be interesting to benchmark it's performance compared to S3 and GCS backends. FWIW, a package which seems to use mongoDB in a similar way to store large binary datasets is https://github.com/manahl/arctic.