We were going to roll our own API across our data sources (we use a few) but decided to give DreamFactory a whirl before we did. It basically stopped us needing to write ETL operations by giving us a gateway that let us avoid data duplication and focus on data quality - leaving the data where it resides and calling it as needed via DreamFactory's clever scripting engine. It has a great reputation for app building, but its also been good spreading across our legacy and modern systems to homogenize everything. We're using it now instead of anything homegrown and it saved us quite a few sprints.