diff --git a/playground/src/test-addons.ts b/playground/src/test-addons.ts
new file mode 100644
index 0000000..bf5e212
--- /dev/null
+++ b/playground/src/test-addons.ts
@@ -0,0 +1,134 @@
+/**
+ * Test script for @hawk.so/nodejs - Testing error addons
+ * This script tests various error types to ensure addons are properly captured
+ */
+import HawkCatcher from '@hawk.so/nodejs';
+import * as fs from 'fs';
+
+/**
+ * Initialize Hawk catcher
+ * Replace with your actual integration token
+ */
+const HAWK_TOKEN = process.env.HAWK_TOKEN || 'eyJpbnRlZ3JhdGlvbklkIjoiNWIwZjBmYmUtNTM2OS00ODM0LWEwMjctNTZkMTM1YmU1OGU3Iiwic2VjcmV0IjoiYWY4ZjY1OTQtNzExOS00MWVmLWI4ZTAtMTcyMDYwZjBmODc2In0=';
+
+console.log('Initializing Hawk Catcher...');
+HawkCatcher.init({
+  token: HAWK_TOKEN,
+  beforeSend: (event) => {
+    console.log('\n--- Event being sent to Hawk ---');
+    console.log('Title:', event.title);
+    console.log('Type:', event.type);
+    console.log('Addons:', JSON.stringify(event.addons, null, 2));
+    console.log('---\n');
+    return event;
+  }
+});
+console.log('Hawk Catcher initialized successfully');
+
+/**
+ * Test 1: Standard Error (no addons expected)
+ */
+function testStandardError(): void {
+  console.log('\n=== Test 1: Standard Error ===');
+  try {
+    throw new Error('Standard error - no additional fields');
+  } catch (error) {
+    if (error instanceof Error) {
+      console.log('Sending standard error...');
+      HawkCatcher.send(error, { test: 'standard-error' });
+    }
+  }
+}
+
+/**
+ * Test 2: Error with Node.js error code
+ */
+function testErrorWithCode(): void {
+  console.log('\n=== Test 2: Error with Node.js Error Code ===');
+  try {
+    const error = new Error('Error with code');
+    // @ts-ignore - adding code property
+    error.code = 'ERR_INVALID_ARG_TYPE';
+    throw error;
+  } catch (error) {
+    if (error instanceof Error) {
+      console.log('Sending error with code...');
+      HawkCatcher.send(error, { test: 'error-with-code' });
+    }
+  }
+}
+
+/**
+ * Test 3: SystemError from file system operation
+ */
+function testSystemError(): void {
+  console.log('\n=== Test 3: SystemError (File System) ===');
+  try {
+    fs.readFileSync('/nonexistent/path/to/file.txt');
+  } catch (error) {
+    if (error instanceof Error) {
+      console.log('Sending SystemError...');
+      HawkCatcher.send(error, { test: 'system-error' });
+    }
+  }
+}
+
+/**
+ * Test 4: Custom error with multiple additional properties
+ */
+function testCustomError(): void {
+  console.log('\n=== Test 4: Custom Error with Multiple Properties ===');
+  try {
+    const error = new Error('Custom error with additional fields');
+    // @ts-ignore - adding custom properties
+    error.code = 'CUSTOM_ERROR_CODE';
+    // @ts-ignore
+    error.statusCode = 500;
+    // @ts-ignore
+    error.details = {
+      userId: 12345,
+      action: 'update_profile',
+      timestamp: new Date().toISOString()
+    };
+    // @ts-ignore
+    error.retryable = true;
+    throw error;
+  } catch (error) {
+    if (error instanceof Error) {
+      console.log('Sending custom error...');
+      HawkCatcher.send(error, { test: 'custom-error' });
+    }
+  }
+}
+
+/**
+ * Test 5: TypeError
+ */
+function testTypeError(): void {
+  console.log('\n=== Test 5: TypeError ===');
+  try {
+    // @ts-ignore - intentional type error
+    null.someProperty();
+  } catch (error) {
+    if (error instanceof Error) {
+      console.log('Sending TypeError...');
+      HawkCatcher.send(error, { test: 'type-error' });
+    }
+  }
+}
+
+/**
+ * Run all tests
+ */
+console.log('\n=== Hawk Playground - Error Addons Test Suite ===\n');
+
+testStandardError();
+setTimeout(() => testErrorWithCode(), 100);
+setTimeout(() => testSystemError(), 200);
+setTimeout(() => testCustomError(), 300);
+setTimeout(() => testTypeError(), 400);
+
+setTimeout(() => {
+  console.log('\n=== All tests completed ===');
+  console.log('Check the console output above to see the addons for each error type.');
+}, 500);
diff --git a/src/index.ts b/src/index.ts
index b09bd89..25fe289 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -227,10 +227,12 @@ class Catcher {
    */
   private formatAndSend(err: Error, context?: EventContext, user?: AffectedUser): void {
     const eventPayload = new EventPayload(err);
+    const addons = eventPayload.getAddons();
     let payload: EventData<NodeJSAddons> = {
       title: eventPayload.getTitle(),
       type: eventPayload.getType(),
       backtrace: eventPayload.getBacktrace(),
+      addons: Object.keys(addons).length > 0 ? addons : undefined,
       user: this.getUser(user),
       context: this.getContext(context),
       release: this.release,
diff --git a/src/modules/event.ts b/src/modules/event.ts
index 2970685..25151c7 100644
--- a/src/modules/event.ts
+++ b/src/modules/event.ts
@@ -1,4 +1,4 @@
-import type { BacktraceFrame } from '@hawk.so/types';
+import type { BacktraceFrame, NodeJSAddons } from '@hawk.so/types';
 import BacktraceHelper from './backtrace.js';
 
 /**
@@ -56,4 +56,79 @@ export default class EventPayload {
 
     return backtrace.getBacktrace();
   }
+
+  /**
+   * Extract additional error information for NodeJS addons
+   * Includes error codes, system error fields, and any custom properties
+   */
+  public getAddons(): NodeJSAddons {
+    if (this.error === undefined) {
+      return {};
+    }
+
+    const addons: NodeJSAddons = {};
+
+    // Get all own properties of the error (including non-enumerable ones)
+    const errorProps = Object.getOwnPropertyNames(this.error);
+
+    // Standard properties to skip (already captured elsewhere)
+    const skipProps = new Set(['name', 'message', 'stack']);
+
+    // Extract all additional properties from the error
+    for (const prop of errorProps) {
+      if (skipProps.has(prop)) {
+        continue;
+      }
+
+      try {
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        const value = (this.error as any)[prop];
+
+        // Only include serializable values (checks for both undefined and null)
+        if (value != null) {
+          // Check if value is JSON-serializable
+          if (this.isSerializable(value)) {
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+            (addons as any)[prop] = value;
+          }
+        }
+      } catch {
+        // Skip properties that can't be accessed
+      }
+    }
+
+    return addons;
+  }
+
+  /**
+   * Check if a value is JSON-serializable
+   * @param value - value to check
+   */
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  private isSerializable(value: any): boolean {
+    const type = typeof value;
+
+    // Primitives are serializable
+    if (type === 'boolean' || type === 'number' || type === 'string') {
+      return true;
+    }
+
+    // Functions and symbols are not serializable
+    if (type === 'function' || type === 'symbol') {
+      return false;
+    }
+
+    // For objects and arrays, try to serialize and catch any errors
+    if (type === 'object') {
+      try {
+        JSON.stringify(value);
+        return true;
+      } catch {
+        // Circular references or other serialization issues
+        return false;
+      }
+    }
+
+    return false;
+  }
 }