---
title: clusteringIdentifier
framework: mapkitjs
role: symbol
role_heading: Interface Property
path: mapkitjs/annotationconstructoroptions/clusteringidentifier
---

# clusteringIdentifier

An identifier for grouping annotations into the same cluster.

## Declaration

```data
clusteringIdentifier?: string | null;
```

## Discussion

Discussion When zooming out on a map that contains many annotations, MapKit JS groups the colliding annotations based on a clustering identifier value. The default value is null. For more information, see Clustering annotations.

## See Also

### Grouping annotations

- [collisionMode](mapkitjs/annotationconstructoroptions/collisionmode.md)
- [id](mapkitjs/annotationconstructoroptions/id.md)