ElasticSearch: geo point clustering

elasticsearch geolocation geospatial geo markerclusterer

I haven't used it but i think you need a geo hash grid aggregation. See: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-geohashgrid-aggregation.html

You should be able to vary your precision and it will return geo_hash buckets with counts of docs.