diff --git a/README.md b/README.md
index cc88e87..b8850ad 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 [![Latest Stable Version](https://poser.pugx.org/donatj/mock-webserver/version)](https://packagist.org/packages/donatj/mock-webserver)
 [![License](https://poser.pugx.org/donatj/mock-webserver/license)](https://packagist.org/packages/donatj/mock-webserver)
 [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/donatj/mock-webserver/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/donatj/mock-webserver)
-[![Build Status](https://github.com/donatj/mock-webserver/workflows/CI/badge.svg?)](https://github.com/donatj/mock-webserver/actions?query=workflow%3ACI)
+[![CI](https://github.com/donatj/mock-webserver/workflows/CI/badge.svg?)](https://github.com/donatj/mock-webserver/actions?query=workflow%3ACI)
 [![Build Status](https://travis-ci.org/donatj/mock-webserver.svg?branch=master)](https://travis-ci.org/donatj/mock-webserver)
 
 
@@ -101,7 +101,7 @@ require __DIR__ . '/../vendor/autoload.php';
 $server = new MockWebServer;
 $server->start();
 
-// We define the servers response to requests of the /definedPath endpoint
+// We define the server's response to requests of the /definedPath endpoint
 $url = $server->setResponseOfPath(
 	'/definedPath',
 	new Response(
@@ -137,6 +137,53 @@ Content-type: text/html; charset=UTF-8
 This is our http body response
 ```
 
+### Change Default Response
+
+```php
+<?php
+
+use donatj\MockWebServer\MockWebServer;
+use donatj\MockWebServer\Responses\NotFoundResponse;
+
+require __DIR__ . '/../vendor/autoload.php';
+
+$server = new MockWebServer;
+$server->start();
+
+// The default response is donatj\MockWebServer\Responses\DefaultResponse
+// which returns an HTTP 200 and a descriptive JSON payload.
+//
+// Change the default response to donatj\MockWebServer\Responses\NotFoundResponse
+// to get a standard 404.
+//
+// Any other response may be specified as default as well.
+$server->setDefaultResponse(new NotFoundResponse);
+
+$content = file_get_contents($server->getServerRoot() . '/PageDoesNotExist', false, stream_context_create([
+	'http' => [ 'ignore_errors' => true ] // allow reading 404s
+]));
+
+// $http_response_header is a little known variable magically defined
+// in the current scope by file_get_contents with the response headers
+echo implode("\n", $http_response_header) . "\n\n";
+echo $content . "\n";
+
+```
+
+Outputs:
+
+```
+HTTP/1.0 404 Not Found
+Host: 127.0.0.1:61355
+Date: Mon, 30 Aug 2021 20:02:58 GMT
+Connection: close
+X-Powered-By: PHP/7.3.29
+Content-type: text/html; charset=UTF-8
+
+VND.DonatStudios.MockWebServer: Resource '/PageDoesNotExist' not found!
+
+```
+
 ### PHPUnit
 
 ```php
diff --git a/docs/docs.md b/docs/docs.md
index 3f43441..707371b 100644
--- a/docs/docs.md
+++ b/docs/docs.md
@@ -115,6 +115,24 @@ Set a specified path to provide a specific response
 
 ---
 
+### Method: MockWebServer->setDefaultResponse
+
+```php
+function setDefaultResponse(\donatj\MockWebServer\ResponseInterface $response)
+```
+
+Override the default server response, e.g. Fallback or 404
+
+#### Parameters:
+
+- ***\donatj\MockWebServer\ResponseInterface*** `$response`
+
+#### Returns:
+
+- ***void***
+
+---
+
 ### Method: MockWebServer->getLastRequest
 
 ```php
@@ -273,4 +291,16 @@ Set the Response for the Given Method
 #### Parameters:
 
 - ***string*** `$method`
-- ***\donatj\MockWebServer\ResponseInterface*** `$response`
\ No newline at end of file
+- ***\donatj\MockWebServer\ResponseInterface*** `$response`
+
+## Built-In Responses
+
+### Class: \donatj\MockWebServer\Responses\DefaultResponse
+
+The Built-In Default Response.
+
+Results in an HTTP 200 with a JSON encoded version of the incoming Request
+
+### Class: \donatj\MockWebServer\Responses\NotFoundResponse
+
+Basic Built-In 404 Response
\ No newline at end of file
diff --git a/example/simple.php b/example/simple.php
index 87d9b05..c8c940f 100644
--- a/example/simple.php
+++ b/example/simple.php
@@ -8,7 +8,7 @@
 $server = new MockWebServer;
 $server->start();
 
-// We define the servers response to requests of the /definedPath endpoint
+// We define the server's response to requests of the /definedPath endpoint
 $url = $server->setResponseOfPath(
 	'/definedPath',
 	new Response(
diff --git a/mddoc.xml b/mddoc.xml
index 9fb7755..e75b67f 100644
--- a/mddoc.xml
+++ b/mddoc.xml
@@ -28,6 +28,10 @@ I would be happy to accept pull requests that correct this.
 						<file name="src/Response.php"/>
 						<file name="src/ResponseStack.php"/>
 						<file name="src/ResponseByMethod.php"/>
+						<section title="Built-In Responses">
+							<file name="src/Responses/DefaultResponse.php"/>
+							<file name="src/Responses/NotFoundResponse.php"/>
+						</section>
 					</section>
 				</docpage>
 			</section>
@@ -49,6 +53,11 @@ I would be happy to accept pull requests that correct this.
 					<text>Outputs:</text>
 					<exec cmd="php example/simple.php" format="code-block" />
 				</section>
+				<section title="Change Default Response">
+					<source name="example/notfound.php" lang="php"/>
+					<text>Outputs:</text>
+					<exec cmd="php example/notfound.php" format="code-block" />
+				</section>
 				<section title="PHPUnit">
 					<source name="example/phpunit.php" lang="php"/>
 				</section>
diff --git a/src/InternalServer.php b/src/InternalServer.php
index 10d83e0..0cd1f37 100644
--- a/src/InternalServer.php
+++ b/src/InternalServer.php
@@ -3,6 +3,8 @@
 namespace donatj\MockWebServer;
 
 use donatj\MockWebServer\Exceptions\ServerException;
+use donatj\MockWebServer\Responses\DefaultResponse;
+use donatj\MockWebServer\Responses\NotFoundResponse;
 
 /**
  * Class InternalServer
@@ -24,6 +26,8 @@ class InternalServer {
 	 */
 	private $header;
 
+	const DEFAULT_REF = 'default';
+
 	/**
 	 * InternalServer constructor.
 	 *
@@ -82,83 +86,121 @@ public static function aliasPath( $tmpPath, $path ) {
 		);
 	}
 
+	/**
+	 * @param string $ref
+	 * @return ResponseInterface|null
+	 */
+	private function responseForRef( $ref ) {
+		$path = $this->tmpPath . DIRECTORY_SEPARATOR . $ref;
+		if( !is_readable($path) ) {
+			return null;
+		}
+
+		$content  = file_get_contents($path);
+		$response = unserialize($content);
+		if( !$response instanceof ResponseInterface ) {
+			throw new ServerException('invalid serialized response');
+		}
+
+		return $response;
+	}
+
 	public function __invoke() {
-		$path = $this->getDataPath();
-
-		if( $path !== false ) {
-			if( is_readable($path) ) {
-				$content  = file_get_contents($path);
-				$response = unserialize($content);
-				if( !$response instanceof ResponseInterface ) {
-					throw new ServerException('invalid serialized response');
-				}
-
-				http_response_code($response->getStatus($this->request));
-
-				foreach( $response->getHeaders($this->request) as $key => $header ) {
-					if( is_int($key) ) {
-						call_user_func($this->header, $header);
-					} else {
-						call_user_func($this->header, "{$key}: {$header}");
-					}
-				}
-				$body = $response->getBody($this->request);
-
-				if( $response instanceof MultiResponseInterface ) {
-					$response->next();
-					self::storeResponse($this->tmpPath, $response);
-				}
-
-				echo $body;
+		$ref = $this->getRefForUri($this->request->getParsedUri()['path']);
+
+		if( $ref !== null ) {
+			$response = $this->responseForRef($ref);
+			if( $response ) {
+				$this->sendResponse($response);
 
 				return;
 			}
 
-			http_response_code(404);
-			echo MockWebServer::VND . ": Resource '{$path}' not found!\n";
+			$this->sendResponse(new NotFoundResponse);
 
 			return;
 		}
 
-		header('Content-Type: application/json');
+		$response = $this->responseForRef(self::DEFAULT_REF);
+		if( $response ) {
+			$this->sendResponse($response);
 
-		echo json_encode($this->request, JSON_PRETTY_PRINT);
+			return;
+		}
+
+		$this->sendResponse(new DefaultResponse);
+	}
+
+	protected function sendResponse( ResponseInterface $response ) {
+		http_response_code($response->getStatus($this->request));
+
+		foreach( $response->getHeaders($this->request) as $key => $header ) {
+			if( is_int($key) ) {
+				call_user_func($this->header, $header);
+			} else {
+				call_user_func($this->header, "{$key}: {$header}");
+			}
+		}
+
+		echo $response->getBody($this->request);
+
+		if( $response instanceof MultiResponseInterface ) {
+			$response->next();
+			self::storeResponse($this->tmpPath, $response);
+		}
 	}
 
 	/**
-	 * @return false|string
+	 * @return string|null
 	 */
-	protected function getDataPath() {
-		$path = false;
-
-		$uriPath   = $this->request->getParsedUri()['path'];
+	protected function getRefForUri( $uriPath ) {
 		$aliasPath = self::aliasPath($this->tmpPath, $uriPath);
+
 		if( file_exists($aliasPath) ) {
 			if( $path = file_get_contents($aliasPath) ) {
-				$path = $this->tmpPath . DIRECTORY_SEPARATOR . $path;
+				return $path;
 			}
-		} elseif( preg_match('%^/' . preg_quote(MockWebServer::VND) . '/([0-9a-fA-F]{32})$%', $uriPath, $matches) ) {
-			$path = $this->tmpPath . DIRECTORY_SEPARATOR . $matches[1];
+		} elseif( preg_match('%^/' . preg_quote(MockWebServer::VND, '%') . '/([0-9a-fA-F]{32})$%', $uriPath, $matches) ) {
+			return $matches[1];
 		}
 
-		return $path;
+		return null;
 	}
 
 	/**
-	 * @internal
 	 * @param string                                  $tmpPath
 	 * @param \donatj\MockWebServer\ResponseInterface $response
 	 * @return string
+	 * @internal
 	 */
 	public static function storeResponse( $tmpPath, ResponseInterface $response ) {
-		$ref     = $response->getRef();
+		$ref = $response->getRef();
+		self::storeRef($response, $tmpPath, $ref);
+
+		return $ref;
+	}
+
+	/**
+	 * @param string                                  $tmpPath
+	 * @param \donatj\MockWebServer\ResponseInterface $response
+	 * @return void
+	 * @internal
+	 */
+	public static function storeDefaultResponse( $tmpPath, ResponseInterface $response ) {
+		self::storeRef($response, $tmpPath, self::DEFAULT_REF);
+	}
+
+	/**
+	 * @param \donatj\MockWebServer\ResponseInterface $response
+	 * @param string                                  $tmpPath
+	 * @param string                                  $ref
+	 */
+	private static function storeRef( ResponseInterface $response, $tmpPath, $ref ) {
 		$content = serialize($response);
 
 		if( !file_put_contents($tmpPath . DIRECTORY_SEPARATOR . $ref, $content) ) {
 			throw new Exceptions\RuntimeException('Failed to write temporary content');
 		}
-
-		return $ref;
 	}
 
 }
diff --git a/src/MockWebServer.php b/src/MockWebServer.php
index 91e4d9b..ca35ceb 100644
--- a/src/MockWebServer.php
+++ b/src/MockWebServer.php
@@ -178,6 +178,16 @@ public function setResponseOfPath( $path, ResponseInterface $response ) {
 		return $this->getServerRoot() . $path;
 	}
 
+	/**
+	 * Override the default server response, e.g. Fallback or 404
+	 *
+	 * @param \donatj\MockWebServer\ResponseInterface $response
+	 * @return void
+	 */
+	public function setDefaultResponse( ResponseInterface $response ) {
+		InternalServer::storeDefaultResponse($this->tmpDir, $response);
+	}
+
 	/**
 	 * @return string
 	 * @internal
diff --git a/src/Responses/DefaultResponse.php b/src/Responses/DefaultResponse.php
new file mode 100644
index 0000000..0687df3
--- /dev/null
+++ b/src/Responses/DefaultResponse.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace donatj\MockWebServer\Responses;
+
+use donatj\MockWebServer\MockWebServer;
+use donatj\MockWebServer\RequestInfo;
+use donatj\MockWebServer\ResponseInterface;
+
+/**
+ * The Built-In Default Response.
+ * Results in an HTTP 200 with a JSON encoded version of the incoming Request
+ */
+class DefaultResponse implements ResponseInterface {
+
+	public function getRef() {
+		return md5(MockWebServer::VND . '.default-ref');
+	}
+
+	public function getBody( RequestInfo $request ) {
+		return json_encode($request, JSON_PRETTY_PRINT) . "\n";
+	}
+
+	public function getHeaders( RequestInfo $request ) {
+		return [ 'Content-Type' => 'application/json' ];
+	}
+
+	public function getStatus( RequestInfo $request ) {
+		return 200;
+	}
+}
diff --git a/src/Responses/NotFoundResponse.php b/src/Responses/NotFoundResponse.php
new file mode 100644
index 0000000..7b6cf40
--- /dev/null
+++ b/src/Responses/NotFoundResponse.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace donatj\MockWebServer\Responses;
+
+use donatj\MockWebServer\MockWebServer;
+use donatj\MockWebServer\RequestInfo;
+use donatj\MockWebServer\ResponseInterface;
+
+/**
+ * Basic Built-In 404 Response
+ */
+class NotFoundResponse implements ResponseInterface {
+
+	public function getRef() {
+		return md5(MockWebServer::VND . '.not-found');
+	}
+
+	public function getBody( RequestInfo $request ) {
+		$path = $request->getParsedUri()['path'];
+
+		return MockWebServer::VND . ": Resource '{$path}' not found!\n";
+	}
+
+	public function getHeaders( RequestInfo $request ) {
+		return [];
+	}
+
+	public function getStatus( RequestInfo $request ) {
+		return 404;
+	}
+}
diff --git a/test/MockWebServer_ChangedDefault_IntegrationTest.php b/test/MockWebServer_ChangedDefault_IntegrationTest.php
new file mode 100644
index 0000000..bde3f55
--- /dev/null
+++ b/test/MockWebServer_ChangedDefault_IntegrationTest.php
@@ -0,0 +1,45 @@
+<?php
+
+use donatj\MockWebServer\MockWebServer;
+use donatj\MockWebServer\Response;
+use donatj\MockWebServer\Responses\NotFoundResponse;
+use PHPUnit\Framework\TestCase;
+
+class MockWebServer_ChangedDefault_IntegrationTest extends TestCase {
+
+	public function testChangingDefaultResponse() {
+		$server = new MockWebServer;
+		$server->start();
+
+		$server->setResponseOfPath('funk', new Response('fresh'));
+		$path = $server->getUrlOfResponse(new Response('fries'));
+
+		$content = file_get_contents($server->getServerRoot() . '/PageDoesNotExist');
+		$result  = json_decode($content, true);
+		$this->assertNotFalse(stripos($http_response_header[0], '200 OK', true) );
+		$this->assertSame('/PageDoesNotExist', $result['PARSED_REQUEST_URI']['path']);
+
+		// try with a 404
+		$server->setDefaultResponse(new NotFoundResponse);
+
+		$content = file_get_contents($server->getServerRoot() . '/PageDoesNotExist', false, stream_context_create([
+			'http' => [ 'ignore_errors' => true ] // allow reading 404s
+		]));
+
+		$this->assertNotFalse(stripos($http_response_header[0], '404 Not Found', true));
+		$this->assertSame("VND.DonatStudios.MockWebServer: Resource '/PageDoesNotExist' not found!\n", $content);
+
+		// try with a custom response
+		$server->setDefaultResponse(new Response('cool beans'));
+		$content = file_get_contents($server->getServerRoot() . '/BadUrlBadTime');
+		$this->assertSame('cool beans', $content);
+
+		// ensure non-404-ing pages countinue to work as expected
+		$content = file_get_contents($server->getServerRoot() . '/funk');
+		$this->assertSame('fresh', $content);
+
+		$content = file_get_contents($path);
+		$this->assertSame('fries', $content);
+	}
+
+}