Geo Data Collector supports GeoJSON

GeoJSON is an open standard for simple geograhical features and non-spatial attributes/properties 

GeoJSON supports the following geometry types: PointLineStringPolygonMultiPointMultiLineString, and MultiPolygon. Geometric objects with additional properties are Feature objects. Sets of features are contained by FeatureCollection objects.

You can use QGIS Desktop, OGR2OGR command line tool and http://geojson.io and other resources to convert data and create GeoJSON

ESRI ArcMap and ArcGIS Pro Geoprocessing tools also supports converting data to GeoJSON JSON To Features (Conversion)