---
title: Clustering annotations
framework: mapkitjs
role: collectionGroup
role_heading: API Collection
path: mapkitjs/clustering-annotations
---

# Clustering annotations

Combine multiple annotations into a single clustered annotation.

## Overview

Overview Annotations display coordinate-specific data on a map, typically in the form of markers or images. To declutter annotation-heavy maps, MapKit JS supports annotation clustering. As the user zooms out on a map that contains annotations, MapKit JS groups individual annotations into a cluster annotation if they collide and if they share the same clusteringIdentifier. The cluster annotation’s memberAnnotations property lists the individual annotations within the cluster. By default, a cluster annotation’s marker displays its member count. MapKit JS creates cluster annotations automatically. Although you can’t instantiate a cluster annotation, you can customize the look of cluster annotations by providing a delegate method, annotationForCluster, to the map. Understand the annotations arrays Although visible on a map, cluster annotations aren’t members of the map’s annotations array. The annotations that make up the cluster do belong to the annotations array, however, even if they’re not individually visible on the map. For example, the following figure shows a map with annotations A, B, C, D, and E:

If the user zooms out so A, B, and C overlap on the map, the annotations combine to create cluster annotation Q, as in the following figure:

The map displays annotations Q, D, and E, and the resulting annotation arrays are: Q.memberAnnotations = [A, B, C]; map.annotations = [A, B, C, D, E]; Set cluster annotation properties Cluster annotations have the same properties as other annotations, but you can’t set some values, including coordinate, clusteringIdentifier, and draggable. Other values have specific defaults as the following table shows:  |  |   |  |   |  |   |  |   |  |   |  |   |  |   |  |

## Topics

- [ClusterAnnotation](mapkitjs/clusterannotation.md)

## See Also

### Annotations

- [Annotation](mapkitjs/annotation.md)
- [ImageAnnotation](mapkitjs/imageannotation.md)
- [MarkerAnnotation](mapkitjs/markerannotation.md)
- [PlaceAnnotation](mapkitjs/placeannotation.md)
- [MapFeatureAnnotation](mapkitjs/mapfeatureannotation.md)
- [UserLocationAnnotation](mapkitjs/userlocationannotation.md)