GeoJSON Map Viewer is a tool that views the GeoJSON file in your browser.
This app allows you to validate your GeoJSON and display it on a Google map.
This app also provides the ability to convert KML, KMZ, GPX, WKT, WKB, TWKB, EWKB, EWKT, TCX, OSM, ZIP(shapefile,dbf,shp), XML(GeoRSS) file to GeoJSON format.
You can view these files including KML, KMZ, GPX directly on the map. 
You can open the files from your computer or Google Drive. Provides connect with Google Drive.

*What is a GeoJSON?
GeoJSON is a format for encoding a variety of geographic data structures.
GeoJSON supports the following geometry types: Point, LineString, Polygon, MultiPoint, MultiLineString, and MultiPolygon.
Lists of geometries are represented by a GeometryCollection. Geometries with additional properties are Feature objects. And lists of features are represented by a FeatureCollection.