1. A method comprising: displaying, at a client device, a first version of a feature in a file or displaying, at the client device, a file having a first format suitable for an editor; and invoking a merge service to request merging of a modification to the file with a master file, the master file supporting a second version of the feature not supported on the client device or the master file supporting a second format different from the first format, wherein the merge service comprises a plurality of application programming interfaces, each application programming interface corresponding to a different modification request, wherein invoking the merge service comprises providing, from the client device to the merge service, a call to a specific application programming interface of the plurality of application programming interfaces, wherein the call comprises a specific modification request to a specific individual modification function and a location identifier that identifies a location of the specific modification request within the file, wherein the specific individual modification function performs adding a comment.