this package levereges the js-marker-clusterer to add clustering support to AGM.

@agm/js-marker-clusterer has a peer depedency on js-marker-clusterer

npm install js-marker-clusterer @agm/js-marker-clusterer --save
# or
yarn add js-marker-clusterer @agm/js-marker-clusterer

1. Import the module

   import { BrowserModule } from '@angular/platform-browser';
   import { NgModule } from '@angular/core';
   import { AppComponent } from './app.component';
   
   // add these imports
   import { AgmCoreModule } from '@agm/core';
   import { AgmJsMarkerClustererModule } from '@agm/js-marker-clusterer';
   
   @NgModule({
     declarations: [
       AppComponent
     ],
     imports: [
       BrowserModule,
       AgmCoreModule.forRoot({
         apiKey: ['YOUR_API_KEY_HERE']
       }),
       AgmJsMarkerClustererModule
     ],
     providers: [],
     bootstrap: [AppComponent]
   })
   export class AppModule { }

2. use it in your template

   <agm-map style="height: 300px" [latitude]="51.673858" [longitude]="7.815982">
     <agm-marker-cluster imagePath="https://raw.githubusercontent.com/googlemaps/v3-utility-library/master/markerclustererplus/images/m">
       <agm-marker [latitude]="51.673858" [longitude]="7.815982">
       </agm-marker><!-- multiple markers -->
     </agm-marker-cluster>
   </agm-map>