AWS Glue, Python Scripting (ArcPy), Koop.JS, GeoEvent, and Geoprocessing services (executed via python script) are also potentials. Depends on the format that you're going to/from, if you need data transformation/processing in the middle, and the level of technical expertise that you're willing to put in. But I would say FME or the ArcGIS Data Interoperability Extension (lighter version of FME) is probably the most powerful and easiest to use.
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