A prominent example is Solr's JSON update endpoint [1], which is just the XML update endpoint in disguise.

It expects input of the form:

    {
       "add": {document 1 goes here},
       "add": {document 2 goes here},
       ...
       "commit": {}
    }

And of course all the "add" values are different and the "commit" has to come at the end.

[1] https://wiki.apache.org/solr/UpdateJSON