diff --git a/.changeset/is-server-property.md b/.changeset/is-server-property.md
new file mode 100644
index 0000000..4645ba5
--- /dev/null
+++ b/.changeset/is-server-property.md
@@ -0,0 +1,5 @@
+---
+"PostHog": minor
+---
+
+Add a configurable `$is_server` event property (default `true`) so PostHog can identify server-side events. Set `PostHogOptions.IsServer` to `false` when using the SDK as a client/CLI so the device OS is attributed normally.
diff --git a/src/PostHog/Api/PostHogApiClient.cs b/src/PostHog/Api/PostHogApiClient.cs
index 1f1a5e2..f188d50 100644
--- a/src/PostHog/Api/PostHogApiClient.cs
+++ b/src/PostHog/Api/PostHogApiClient.cs
@@ -285,6 +285,12 @@ void PrepareAndMutatePayload(Dictionary<string, object> payload)
 
         properties.Merge(_options.Value.SuperProperties);
 
+        // Stamp $is_server last so a super property can't override the SDK's server/client classification.
+        if (_options.Value.IsServer)
+        {
+            properties[PostHogProperties.IsServer] = true;
+        }
+
         payload["properties"] = properties;
 
         // Only set timestamp if one isn't already provided in properties
diff --git a/src/PostHog/Api/PostHogProperties.cs b/src/PostHog/Api/PostHogProperties.cs
index 9f178a1..b295765 100644
--- a/src/PostHog/Api/PostHogProperties.cs
+++ b/src/PostHog/Api/PostHogProperties.cs
@@ -15,6 +15,11 @@ public static class PostHogProperties
     /// </summary>
     public const string Lib = "$lib";
 
+    /// <summary>
+    /// The property name indicating that the event was captured by a server-side SDK.
+    /// </summary>
+    public const string IsServer = "$is_server";
+
     /// <summary>
     /// The property name for the client library version.
     /// </summary>
diff --git a/src/PostHog/Config/PostHogOptions.cs b/src/PostHog/Config/PostHogOptions.cs
index b8c143e..c6a92e6 100644
--- a/src/PostHog/Config/PostHogOptions.cs
+++ b/src/PostHog/Config/PostHogOptions.cs
@@ -67,6 +67,20 @@ public string? ProjectApiKey
     /// </remarks>
     public IReadOnlyList<string>? EvaluationContexts { get; set; }
 
+    /// <summary>
+    /// Whether captured events are attributed to a server. (Default: true)
+    /// </summary>
+    /// <remarks>
+    /// When <c>true</c> (the default), every captured event includes the <c>$is_server</c> property set to
+    /// <c>true</c> so PostHog identifies the event as server-side. Set this to <c>false</c> when using the SDK
+    /// as a client or CLI so the device's operating system is attributed normally instead of being treated as a
+    /// server. When <c>false</c>, the <c>$is_server</c> property is omitted entirely.
+    /// <code>
+    /// var options = new PostHogOptions { ProjectToken = "phc_...", IsServer = false };
+    /// </code>
+    /// </remarks>
+    public bool IsServer { get; set; } = true;
+
     /// <summary>
     /// Whether this client is disabled and should no-op instead of sending data to PostHog. (Default: false)
     /// </summary>
diff --git a/src/PostHog/PostHogClient.cs b/src/PostHog/PostHogClient.cs
index 68370e1..ad9475e 100644
--- a/src/PostHog/PostHogClient.cs
+++ b/src/PostHog/PostHogClient.cs
@@ -313,6 +313,12 @@ bool CaptureCore(
 
         capturedEvent.Properties.Merge(_options.Value.SuperProperties);
 
+        // Stamp $is_server last so a super property can't override the SDK's server/client classification.
+        if (_options.Value.IsServer)
+        {
+            capturedEvent.Properties[PostHogProperties.IsServer] = true;
+        }
+
         var batchItem = new BatchItem<CapturedEvent, CapturedEventBatchContext>(BatchTask);
 
         if (_asyncBatchHandler.Enqueue(batchItem))
diff --git a/tests/UnitTests/Features/FeatureFlagsTests.cs b/tests/UnitTests/Features/FeatureFlagsTests.cs
index b05fffa..5ce3977 100644
--- a/tests/UnitTests/Features/FeatureFlagsTests.cs
+++ b/tests/UnitTests/Features/FeatureFlagsTests.cs
@@ -197,7 +197,8 @@ public async Task CapturesFeatureFlagCalledEventOnlyOncePerDistinctIdFlagKeyAndR
                       "distinct_id": "a-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   },
@@ -215,7 +216,8 @@ public async Task CapturesFeatureFlagCalledEventOnlyOncePerDistinctIdFlagKeyAndR
                       "distinct_id": "another-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   },
@@ -233,7 +235,8 @@ public async Task CapturesFeatureFlagCalledEventOnlyOncePerDistinctIdFlagKeyAndR
                       "distinct_id": "another-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   }
@@ -290,7 +293,8 @@ public async Task CapturesFeatureFlagCalledEventOnlyOncePerDistinctIdFlagKeyAndR
                       "distinct_id": "a-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   },
@@ -306,7 +310,8 @@ public async Task CapturesFeatureFlagCalledEventOnlyOncePerDistinctIdFlagKeyAndR
                       "distinct_id": "another-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   },
@@ -322,7 +327,8 @@ public async Task CapturesFeatureFlagCalledEventOnlyOncePerDistinctIdFlagKeyAndR
                       "distinct_id": "another-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   }
@@ -498,7 +504,8 @@ await client.IsFeatureEnabledAsync(
                       "distinct_id": "659df793-429a-4517-84ff-747dfc103e6c",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{VersionConstants.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   }
@@ -549,7 +556,8 @@ public async Task CapturesFeatureFlagCalledEventWithRequestIdWhenPresent()
                       "distinct_id": "a-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   }
@@ -601,7 +609,8 @@ public async Task CapturesFeatureFlagCalledEventWithoutEvaluatedAtWhenNotPresent
                       "distinct_id": "a-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   }
@@ -729,7 +738,8 @@ public async Task CapturesFeatureFlagCalledEventWithAdditionalMetadataIdWhenPres
                       "distinct_id": "a-distinct-id",
                       "$lib": "posthog-dotnet",
                       "$lib_version": "{{client.Version}}",
-                      "$geoip_disable": true
+                      "$geoip_disable": true,
+                      "$is_server": true
                     },
                     "timestamp": "2024-01-21T19:08:23\u002B00:00"
                   }
@@ -2455,7 +2465,8 @@ public async Task CapturesFeatureFlagCalledEvent()
                                "distinct_id": "a-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:23\u002B00:00"
                            }
@@ -2508,7 +2519,8 @@ public async Task CapturesFeatureFlagCalledEventWithGroupInformation()
                                "$groups": {
                                  "company": "id:5",
                                  "department": "id:3"
-                               }
+                               },
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:23\u002B00:00"
                            }
@@ -2569,7 +2581,8 @@ await client.GetFeatureFlagAsync("another-flag-key",
                                "distinct_id": "a-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:23\u002B00:00"
                            },
@@ -2585,7 +2598,8 @@ await client.GetFeatureFlagAsync("another-flag-key",
                                "distinct_id": "another-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:24\u002B00:00"
                            },
@@ -2601,7 +2615,8 @@ await client.GetFeatureFlagAsync("another-flag-key",
                                "distinct_id": "another-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:25\u002B00:00"
                            },
@@ -2617,7 +2632,8 @@ await client.GetFeatureFlagAsync("another-flag-key",
                                "distinct_id": "a-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:27\u002B00:00"
                            }
@@ -2673,7 +2689,8 @@ public async Task CapturesFeatureFlagCalledEventAgainIfCacheSlidingWindowExpirat
                                "distinct_id": "a-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:23\u002B00:00"
                            },
@@ -2689,7 +2706,8 @@ public async Task CapturesFeatureFlagCalledEventAgainIfCacheSlidingWindowExpirat
                                "distinct_id": "another-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:24\u002B00:00"
                            },
@@ -2705,7 +2723,8 @@ public async Task CapturesFeatureFlagCalledEventAgainIfCacheSlidingWindowExpirat
                                "distinct_id": "another-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:25\u002B00:00"
                            },
@@ -2721,7 +2740,8 @@ public async Task CapturesFeatureFlagCalledEventAgainIfCacheSlidingWindowExpirat
                                "distinct_id": "a-distinct-id",
                                "$lib": "posthog-dotnet",
                                "$lib_version": "{{client.Version}}",
-                               "$geoip_disable": true
+                               "$geoip_disable": true,
+                               "$is_server": true
                              },
                              "timestamp": "2024-01-21T19:08:27\u002B00:00"
                            }
diff --git a/tests/UnitTests/PostHogClientTests.cs b/tests/UnitTests/PostHogClientTests.cs
index b2241a6..4009ae0 100644
--- a/tests/UnitTests/PostHogClientTests.cs
+++ b/tests/UnitTests/PostHogClientTests.cs
@@ -33,6 +33,43 @@ public async Task SendsCorrectPayload()
 
         Assert.Equal(1, result.Status);
         var received = requestHandler.GetReceivedRequestBody(indented: true);
+        Assert.Equal($$"""
+                       {
+                         "event": "$identify",
+                         "distinct_id": "some-distinct-id",
+                         "properties": {
+                           "$lib": "posthog-dotnet",
+                           "$lib_version": "{{VersionConstants.Version}}",
+                           "$os": "{{RuntimeInformation.OSDescription}}",
+                           "$framework": "{{RuntimeInformation.FrameworkDescription}}",
+                           "$arch": "{{RuntimeInformation.ProcessArchitecture}}",
+                           "$geoip_disable": true,
+                           "$is_server": true
+                         },
+                         "api_key": "fake-project-token",
+                         "timestamp": "2024-01-21T19:08:23\u002B00:00"
+                       }
+                       """, received);
+    }
+
+    [Fact]
+    public async Task OmitsIsServerWhenIsServerOptionIsFalse()
+    {
+        var container = new TestContainer(services => services.Configure<PostHogOptions>(options =>
+        {
+            options.ProjectToken = "fake-project-token";
+            options.EnableCompression = false;
+            options.IsServer = false;
+        }));
+        container.FakeTimeProvider.SetUtcNow(new DateTimeOffset(2024, 1, 21, 19, 08, 23, TimeSpan.Zero));
+        var requestHandler = container.FakeHttpMessageHandler.AddCaptureResponse();
+        var client = container.Activate<PostHogClient>();
+
+        var result = await client.IdentifyAsync("some-distinct-id");
+
+        Assert.Equal(1, result.Status);
+        var received = requestHandler.GetReceivedRequestBody(indented: true);
+        Assert.DoesNotContain("$is_server", received, StringComparison.Ordinal);
         Assert.Equal($$"""
                        {
                          "event": "$identify",
@@ -73,7 +110,8 @@ public async Task SendsCorrectPayloadWithGeoIpEnabled()
                            "$os": "{{RuntimeInformation.OSDescription}}",
                            "$framework": "{{RuntimeInformation.FrameworkDescription}}",
                            "$arch": "{{RuntimeInformation.ProcessArchitecture}}",
-                           "$geoip_disable": false
+                           "$geoip_disable": false,
+                           "$is_server": true
                          },
                          "api_key": "fake-project-token",
                          "timestamp": "2024-01-21T19:08:23\u002B00:00"
@@ -117,7 +155,8 @@ public async Task SendsCorrectPayloadWithPersonProperties()
                            "$os": "{{RuntimeInformation.OSDescription}}",
                            "$framework": "{{RuntimeInformation.FrameworkDescription}}",
                            "$arch": "{{RuntimeInformation.ProcessArchitecture}}",
-                           "$geoip_disable": true
+                           "$geoip_disable": true,
+                           "$is_server": true
                          },
                          "api_key": "fake-project-token",
                          "timestamp": "2024-01-21T19:08:23\u002B00:00"
@@ -156,7 +195,8 @@ public async Task SendsCorrectPayloadWithSuperProperties()
                            "$framework": "{{RuntimeInformation.FrameworkDescription}}",
                            "$arch": "{{RuntimeInformation.ProcessArchitecture}}",
                            "$geoip_disable": true,
-                           "source": "repo-name"
+                           "source": "repo-name",
+                           "$is_server": true
                          },
                          "api_key": "fake-project-token",
                          "timestamp": "2024-01-21T19:08:23\u002B00:00"
@@ -194,7 +234,8 @@ public async Task SendsCorrectPayload()
                            "$os": "{{RuntimeInformation.OSDescription}}",
                            "$framework": "{{RuntimeInformation.FrameworkDescription}}",
                            "$arch": "{{RuntimeInformation.ProcessArchitecture}}",
-                           "$geoip_disable": true
+                           "$geoip_disable": true,
+                           "$is_server": true
                          },
                          "api_key": "fake-project-token",
                          "timestamp": "2024-01-21T19:08:23\u002B00:00"
@@ -229,7 +270,8 @@ public async Task SendsCorrectPayloadWithUserProvidedDistinctId()
                            "$os": "{{RuntimeInformation.OSDescription}}",
                            "$framework": "{{RuntimeInformation.FrameworkDescription}}",
                            "$arch": "{{RuntimeInformation.ProcessArchitecture}}",
-                           "$geoip_disable": true
+                           "$geoip_disable": true,
+                           "$is_server": true
                          },
                          "api_key": "fake-project-token",
                          "timestamp": "2024-01-21T19:08:23\u002B00:00"
@@ -278,6 +320,7 @@ public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotM
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/flag1": true,
                              "$feature/flag2": false,
                              "$feature/flag3": "variant-0",
@@ -297,6 +340,7 @@ public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotM
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/flag1": true,
                              "$feature/flag2": false,
                              "$feature/flag3": "variant-0",
@@ -316,6 +360,7 @@ public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotM
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/flag1": true,
                              "$feature/flag2": false,
                              "$feature/flag3": "variant-1",
@@ -335,6 +380,7 @@ public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotM
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/flag1": true,
                              "$feature/flag2": false,
                              "$feature/flag3": "variant-0",
@@ -354,6 +400,7 @@ public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotM
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/flag1": true,
                              "$feature/flag2": false,
                              "$feature/flag3": "variant-0",
@@ -373,6 +420,7 @@ public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotM
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/flag1": true,
                              "$feature/flag2": false,
                              "$feature/flag3": "variant-1",
@@ -392,6 +440,7 @@ public async Task SendsEnrichedCapturedEventsWhenSendFeatureFlagsTrueButDoesNotM
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/flag1": true,
                              "$feature/flag2": false,
                              "$feature/flag3": "variant-2",
@@ -435,7 +484,8 @@ public async Task CaptureWithCustomTimestampUsesProvidedTimestamp()
                              "distinct_id": "test-user",
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
-                             "$geoip_disable": true
+                             "$geoip_disable": true,
+                             "$is_server": true
                            },
                            "timestamp": "2023-12-25T10:30:45\u002B00:00"
                          }
@@ -473,7 +523,8 @@ public async Task CaptureWithTimestampAndPropertiesUsesProvidedTimestamp()
                              "distinct_id": "test-user",
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
-                             "$geoip_disable": true
+                             "$geoip_disable": true,
+                             "$is_server": true
                            },
                            "timestamp": "2023-12-25T10:30:45\u002B00:00"
                          }
@@ -513,7 +564,8 @@ public async Task CaptureWithTimestampAndGroupsUsesProvidedTimestamp()
                              "$geoip_disable": true,
                              "$groups": {
                                "company": "acme-corp"
-                             }
+                             },
+                             "$is_server": true
                            },
                            "timestamp": "2023-12-25T10:30:45\u002B00:00"
                          }
@@ -551,6 +603,7 @@ public async Task CaptureWithTimestampAndFeatureFlagsUsesProvidedTimestamp()
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/test-flag": true,
                              "$active_feature_flags": [
                                "test-flag"
@@ -596,7 +649,8 @@ public async Task CaptureWithTimestampPropertiesAndGroupsUsesProvidedTimestamp()
                              "$geoip_disable": true,
                              "$groups": {
                                "company": "acme-corp"
-                             }
+                             },
+                             "$is_server": true
                            },
                            "timestamp": "2023-12-25T10:30:45\u002B00:00"
                          }
@@ -640,6 +694,7 @@ public async Task CaptureWithAllParametersAndTimestampUsesProvidedTimestamp()
                              "$groups": {
                                "company": "acme-corp"
                              },
+                             "$is_server": true,
                              "$feature/test-flag": true,
                              "$active_feature_flags": [
                                "test-flag"
@@ -686,7 +741,8 @@ public async Task CaptureWithTimestampParameterOverridesTimestampInProperties()
                              "distinct_id": "test-user",
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
-                             "$geoip_disable": true
+                             "$geoip_disable": true,
+                             "$is_server": true
                            },
                            "timestamp": "2023-12-25T10:30:45\u002B00:00"
                          }
@@ -762,6 +818,7 @@ public async Task CaptureWithSendFeatureFlagsTrueAndLocalEvaluationEnabledUsesLo
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
                              "$geoip_disable": true,
+                             "$is_server": true,
                              "$feature/local-flag": true,
                              "$feature/another-local-flag": true,
                              "$active_feature_flags": [
@@ -828,7 +885,8 @@ public async Task CaptureWithSendFeatureFlagsFalseDoesNotAddFeatureFlagsEvenWhen
                              "distinct_id": "test-distinct-id",
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
-                             "$geoip_disable": true
+                             "$geoip_disable": true,
+                             "$is_server": true
                            },
                            "timestamp": "2024-01-21T19:08:23\u002B00:00"
                          }
@@ -890,7 +948,8 @@ public async Task CaptureDefaultsToNotSendingFeatureFlagsEvenWhenLocalEvaluation
                              "distinct_id": "test-distinct-id",
                              "$lib": "posthog-dotnet",
                              "$lib_version": "{{VersionConstants.Version}}",
-                             "$geoip_disable": true
+                             "$geoip_disable": true,
+                             "$is_server": true
                            },
                            "timestamp": "2024-01-21T19:08:23\u002B00:00"
                          }
@@ -925,6 +984,7 @@ public async Task CaptureExceptionWithDivideByZeroException() // based on PostHo
             Assert.Equal("System.DivideByZeroException", props.GetProperty("$exception_type").GetString());
             Assert.Contains("divide by zero", props.GetProperty("$exception_message").GetString(), StringComparison.OrdinalIgnoreCase);
             Assert.Equal("posthog-dotnet", props.GetProperty("$lib").GetString());
+            Assert.True(props.GetProperty("$is_server").GetBoolean());
             Assert.Equal(VersionConstants.Version, props.GetProperty("$lib_version").GetString());
 
             var firstException = GetFirstException(props);