diff --git a/scm-webapp/src/main/java/sonia/scm/api/v2/resources/AvailablePluginResource.java b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/AvailablePluginResource.java
index 3ee4a4ea73..dab5c2652e 100644
--- a/scm-webapp/src/main/java/sonia/scm/api/v2/resources/AvailablePluginResource.java
+++ b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/AvailablePluginResource.java
@@ -4,7 +4,7 @@ import com.webcohesion.enunciate.metadata.rs.ResponseCode;
 import com.webcohesion.enunciate.metadata.rs.StatusCodes;
 import com.webcohesion.enunciate.metadata.rs.TypeHint;
 import sonia.scm.plugin.AvailablePlugin;
-import sonia.scm.plugin.InstalledPluginDescriptor;
+import sonia.scm.plugin.InstalledPlugin;
 import sonia.scm.plugin.PluginManager;
 import sonia.scm.plugin.PluginPermissions;
 import sonia.scm.web.VndMediaType;
@@ -19,6 +19,7 @@ import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.Response;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 import static sonia.scm.ContextEntry.ContextBuilder.entity;
 import static sonia.scm.NotFoundException.notFound;
@@ -51,10 +52,15 @@ public class AvailablePluginResource {
   @Produces(VndMediaType.PLUGIN_COLLECTION)
   public Response getAvailablePlugins() {
     PluginPermissions.read().check();
-    List<AvailablePlugin> available = pluginManager.getAvailable();
+    List<InstalledPlugin> installed = pluginManager.getInstalled();
+    List<AvailablePlugin> available = pluginManager.getAvailable().stream().filter(a -> notInstalled(a, installed)).collect(Collectors.toList());
     return Response.ok(collectionMapper.mapAvailable(available)).build();
   }
 
+  private boolean notInstalled(AvailablePlugin a, List<InstalledPlugin> installed) {
+    return installed.stream().noneMatch(installedPlugin -> installedPlugin.getDescriptor().getInformation().getName().equals(a.getDescriptor().getInformation().getName()));
+  }
+
   /**
    * Returns available plugin.
    *
diff --git a/scm-webapp/src/test/java/sonia/scm/api/v2/resources/AvailablePluginResourceTest.java b/scm-webapp/src/test/java/sonia/scm/api/v2/resources/AvailablePluginResourceTest.java
index c108d4ee7a..436e0b630a 100644
--- a/scm-webapp/src/test/java/sonia/scm/api/v2/resources/AvailablePluginResourceTest.java
+++ b/scm-webapp/src/test/java/sonia/scm/api/v2/resources/AvailablePluginResourceTest.java
@@ -18,6 +18,8 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import sonia.scm.plugin.AvailablePlugin;
 import sonia.scm.plugin.AvailablePluginDescriptor;
+import sonia.scm.plugin.InstalledPlugin;
+import sonia.scm.plugin.InstalledPluginDescriptor;
 import sonia.scm.plugin.PluginCondition;
 import sonia.scm.plugin.PluginInformation;
 import sonia.scm.plugin.PluginManager;
@@ -25,7 +27,6 @@ import sonia.scm.web.VndMediaType;
 
 import javax.inject.Provider;
 import javax.servlet.http.HttpServletResponse;
-
 import java.io.UnsupportedEncodingException;
 import java.net.URISyntaxException;
 import java.util.Collections;
@@ -34,6 +35,7 @@ import java.util.Optional;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.lenient;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -90,9 +92,10 @@ class AvailablePluginResourceTest {
 
     @Test
     void getAvailablePlugins() throws URISyntaxException, UnsupportedEncodingException {
-      AvailablePlugin plugin = createPlugin();
+      AvailablePlugin plugin = createAvailablePlugin();
 
       when(pluginManager.getAvailable()).thenReturn(Collections.singletonList(plugin));
+      when(pluginManager.getInstalled()).thenReturn(Collections.emptyList());
       when(collectionMapper.mapAvailable(Collections.singletonList(plugin))).thenReturn(new MockedResultDto());
 
       MockHttpRequest request = MockHttpRequest.get("/v2/plugins/available");
@@ -105,13 +108,32 @@ class AvailablePluginResourceTest {
       assertThat(response.getContentAsString()).contains("\"marker\":\"x\"");
     }
 
+    @Test
+    void shouldNotReturnInstalledPlugins() throws URISyntaxException, UnsupportedEncodingException {
+      AvailablePlugin availablePlugin = createAvailablePlugin();
+      InstalledPlugin installedPlugin = createInstalledPlugin();
+
+      when(pluginManager.getAvailable()).thenReturn(Collections.singletonList(availablePlugin));
+      when(pluginManager.getInstalled()).thenReturn(Collections.singletonList(installedPlugin));
+      lenient().when(collectionMapper.mapAvailable(Collections.singletonList(availablePlugin))).thenReturn(new MockedResultDto());
+
+      MockHttpRequest request = MockHttpRequest.get("/v2/plugins/available");
+      request.accept(VndMediaType.PLUGIN_COLLECTION);
+      MockHttpResponse response = new MockHttpResponse();
+
+      dispatcher.invoke(request, response);
+
+      assertThat(HttpServletResponse.SC_OK).isEqualTo(response.getStatus());
+      assertThat(response.getContentAsString()).doesNotContain("\"marker\":\"x\"");
+    }
+
     @Test
     void getAvailablePlugin() throws UnsupportedEncodingException, URISyntaxException {
       PluginInformation pluginInformation = new PluginInformation();
       pluginInformation.setName("pluginName");
       pluginInformation.setVersion("2.0.0");
 
-      AvailablePlugin plugin = createPlugin(pluginInformation);
+      AvailablePlugin plugin = createAvailablePlugin(pluginInformation);
 
       when(pluginManager.getAvailable("pluginName")).thenReturn(Optional.of(plugin));
 
@@ -152,17 +174,31 @@ class AvailablePluginResourceTest {
     }
   }
 
-  private AvailablePlugin createPlugin() {
-    return createPlugin(new PluginInformation());
+  private AvailablePlugin createAvailablePlugin() {
+    PluginInformation pluginInformation = new PluginInformation();
+    pluginInformation.setName("scm-some-plugin");
+    return createAvailablePlugin(pluginInformation);
   }
 
-  private AvailablePlugin createPlugin(PluginInformation pluginInformation) {
+  private AvailablePlugin createAvailablePlugin(PluginInformation pluginInformation) {
     AvailablePluginDescriptor descriptor = new AvailablePluginDescriptor(
       pluginInformation, new PluginCondition(), Collections.emptySet(), "https://download.hitchhiker.com", null
     );
     return new AvailablePlugin(descriptor);
   }
 
+  private InstalledPlugin createInstalledPlugin() {
+    PluginInformation pluginInformation = new PluginInformation();
+    pluginInformation.setName("scm-some-plugin");
+    return createInstalledPlugin(pluginInformation);
+  }
+
+  private InstalledPlugin createInstalledPlugin(PluginInformation pluginInformation) {
+    InstalledPluginDescriptor descriptor = mock(InstalledPluginDescriptor.class);
+    lenient().when(descriptor.getInformation()).thenReturn(pluginInformation);
+    return new InstalledPlugin(descriptor, null, null, null, false);
+  }
+
   @Nested
   class WithoutAuthorization {