The Data Flow API offers two output formats: JSON & CSV.
This format can be chosen at the bottom right of the interface or changed in the URL directly:
Note: the format can be changed on the fly in the API URL. It is not mandatory to save the flow with the new configuration.
Advice: JSON format is heavier than CSV; for a quicker download, we recommend that you choose the CSV format. If you'd rather download a JSON format anyway, please make sure you enable compression in the header of your API call.