I want to make Choropleth map in Openlayers 3 which is already implemented in Leaflet but not in Openlayers 3. how to integrate 'colorbrewer' in Openlayers 3? Give the working example of it.
You can use this thematic mapping api which provides choropleth using open layers using GEOJSON and KML both.
Please have a look on this api
There is also another API which provides live demo here
openlayers 2 is working but for openlayers 3 there is still search in progress. Dynamic sld is one option with open layers 3.