We have a public web map that shows the locations of algal blooms. It is a simple map and I'd like to do something with apps to make it more visually appealing and intuitive. One of the requirements is that people must be able to filter and download their data. Which apps allow for data to be downloaded, either in CSV, xls, shapefile, etc?
I think you may be able to accomplish this using the Web App Builder. Take a look at the select widget: Select widget—Web AppBuilder for ArcGIS | ArcGIS
As an alternative, but much more limited than the option provided by Kelly (export to CSV only) is using the Attribute Table widget—Web AppBuilder for ArcGIS | ArcGIS . You will have to check the option "Allow to export to CSV" in the configuration.