diff --git a/README.md b/README.md
index 724d0ef..2508f5d 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,37 @@ How the response is looked up:
 * **Media type**: the response's `Content-Type`, including `+json` types such as `application/problem+json`.
   Without a match it falls back to `application/json`. Only JSON bodies are validated.
 
+### Guzzle and PSR-18 clients
+Verifying on the client side needs no framework. It works against a running server, a mock
+handler or anything else a client can talk to.
+
+**Guzzle**: push the middleware onto the handler stack. A response that does not match makes the
+request throw `OpenApiSchemaMismatchException`.
+
+```php
+use GuzzleHttp\Client;
+use GuzzleHttp\HandlerStack;
+use Radebatz\OpenApi\Verifier\Adapters\Guzzle\OpenApiVerifierMiddleware;
+use Radebatz\OpenApi\Verifier\OpenApiVerifier;
+
+$stack = HandlerStack::create();
+$stack->push(new OpenApiVerifierMiddleware(OpenApiVerifier::fromSpecification('openapi.yaml')), 'openapi-verifier');
+
+$client = new Client(['handler' => $stack, 'base_uri' => 'http://localhost:8080']);
+$client->get('/user/1'); // verified against `/user/{id}`
+```
+
+**PSR-18**: wrap any `Psr\Http\Client\ClientInterface`, Guzzle's included.
+
+```php
+use Radebatz\OpenApi\Verifier\Adapters\Psr18\OpenApiVerifyingClient;
+
+$client = new OpenApiVerifyingClient($psr18Client, OpenApiVerifier::fromSpecification('openapi.yaml'));
+$response = $client->sendRequest($request);
+```
+
+Either way the response body is left at its start, so it can be read as usual afterwards.
+
 ### Manual verification
 The `VerifiesOpenApi` trait can be used directly and customized in 3 ways in order to provide the reqired OpenApi specifications:
 * Overriding the method `getOpenApiSpecificationLoader()` as shown below
diff --git a/composer.json b/composer.json
index 5eecde5..0981971 100644
--- a/composer.json
+++ b/composer.json
@@ -56,11 +56,13 @@
         "justinrainbow/json-schema": "^5.2.13 || ^6",
         "nyholm/psr7": "^1.1",
         "nyholm/psr7-server": "^1.0",
+        "psr/http-client": "^1.0",
         "psr/http-message": "^2.0",
         "symfony/psr-http-message-bridge": "^6.0 || ^7.0"
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^3.62.0",
+        "guzzlehttp/guzzle": "^7.8",
         "laravel/laravel": "^12.0 || ^13.0",
         "league/container": "^4.2",
         "phpstan/phpstan": "^2.1",
@@ -71,6 +73,7 @@
         "zircote/swagger-php": "^4.8 || ^5.0 || ^6.0"
     },
     "suggest": {
+        "guzzlehttp/guzzle": "To verify responses in a Guzzle client, with the Guzzle middleware",
         "laravel/framework": "To use the Laravel adapter",
         "slim/slim": "To use the Slim adapter",
         "zircote/swagger-php": "To generate the specification from PHP attributes when none is given"
diff --git a/src/Adapters/Guzzle/OpenApiVerifierMiddleware.php b/src/Adapters/Guzzle/OpenApiVerifierMiddleware.php
new file mode 100644
index 0000000..77f6476
--- /dev/null
+++ b/src/Adapters/Guzzle/OpenApiVerifierMiddleware.php
@@ -0,0 +1,37 @@
+<?php declare(strict_types=1);
+
+namespace Radebatz\OpenApi\Verifier\Adapters\Guzzle;
+
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use Radebatz\OpenApi\Verifier\OpenApiVerifier;
+
+/**
+ * Guzzle handler middleware verifying every response against the specification.
+ *
+ * A mismatch rejects the response's promise, so a synchronous request throws
+ * `OpenApiSchemaMismatchException`.
+ *
+ * ```php
+ * $stack = HandlerStack::create();
+ * $stack->push(new OpenApiVerifierMiddleware($verifier), 'openapi-verifier');
+ * $client = new Client(['handler' => $stack]);
+ * ```
+ */
+final class OpenApiVerifierMiddleware
+{
+    public function __construct(private readonly OpenApiVerifier $verifier)
+    {
+    }
+
+    public function __invoke(callable $handler): callable
+    {
+        return fn (RequestInterface $request, array $options) => $handler($request, $options)->then(
+            function (ResponseInterface $response) use ($request): ResponseInterface {
+                $this->verifier->verify($request, $response);
+
+                return $response;
+            }
+        );
+    }
+}
diff --git a/src/Adapters/Psr18/OpenApiVerifyingClient.php b/src/Adapters/Psr18/OpenApiVerifyingClient.php
new file mode 100644
index 0000000..309f779
--- /dev/null
+++ b/src/Adapters/Psr18/OpenApiVerifyingClient.php
@@ -0,0 +1,32 @@
+<?php declare(strict_types=1);
+
+namespace Radebatz\OpenApi\Verifier\Adapters\Psr18;
+
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use Radebatz\OpenApi\Verifier\OpenApiVerifier;
+
+/**
+ * A PSR-18 client verifying every response it receives against the specification.
+ *
+ * Throws `OpenApiSchemaMismatchException` on a mismatch, which is not a PSR-18 client exception:
+ * the request was sent, the response just does not match.
+ */
+final class OpenApiVerifyingClient implements ClientInterface
+{
+    public function __construct(
+        private readonly ClientInterface $client,
+        private readonly OpenApiVerifier $verifier,
+    ) {
+    }
+
+    public function sendRequest(RequestInterface $request): ResponseInterface
+    {
+        $response = $this->client->sendRequest($request);
+
+        $this->verifier->verify($request, $response);
+
+        return $response;
+    }
+}
diff --git a/src/OpenApiVerifier.php b/src/OpenApiVerifier.php
index 8eeadbb..ca0c4f4 100644
--- a/src/OpenApiVerifier.php
+++ b/src/OpenApiVerifier.php
@@ -43,11 +43,18 @@ public function getSpecificationLoader(): OpenApiSpecificationLoader
      */
     public function verify(RequestInterface $request, ResponseInterface $response, ?string $pathTemplate = null): bool
     {
+        $body = $response->getBody();
+        $content = (string) $body;
+        if ($body->isSeekable()) {
+            // the caller reads the body next, and casting left the stream at its end
+            $body->rewind();
+        }
+
         return $this->verifyResponseBody(
             $request->getMethod(),
             $pathTemplate ?? $request->getUri()->getPath(),
             $response->getStatusCode(),
-            (string) $response->getBody(),
+            $content,
             $response->getHeaderLine('Content-Type') ?: null
         );
     }
diff --git a/tests/Adapters/ClientAdapterTest.php b/tests/Adapters/ClientAdapterTest.php
new file mode 100644
index 0000000..c650112
--- /dev/null
+++ b/tests/Adapters/ClientAdapterTest.php
@@ -0,0 +1,86 @@
+<?php declare(strict_types=1);
+
+namespace Radebatz\OpenApi\Verifier\Tests\Adapters;
+
+use GuzzleHttp\Client;
+use GuzzleHttp\Handler\MockHandler;
+use GuzzleHttp\HandlerStack;
+use GuzzleHttp\Psr7\Request;
+use GuzzleHttp\Psr7\Response;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ResponseInterface;
+use Radebatz\OpenApi\Verifier\Adapters\Guzzle\OpenApiVerifierMiddleware;
+use Radebatz\OpenApi\Verifier\Adapters\Psr18\OpenApiVerifyingClient;
+use Radebatz\OpenApi\Verifier\OpenApiSchemaMismatchException;
+use Radebatz\OpenApi\Verifier\OpenApiVerifier;
+
+class ClientAdapterTest extends TestCase
+{
+    protected function verifier(): OpenApiVerifier
+    {
+        return OpenApiVerifier::fromSpecification(__DIR__ . '/../specifications/users.yaml');
+    }
+
+    public static function responses(): iterable
+    {
+        // path, body, expected error (null: valid)
+        yield 'users' => ['/users', '{"data":[{"id":1,"name":"joe","email":"joe@cool.com"}]}', null];
+        yield 'users mismatch' => ['/users', '{"data":[{"id":1,"email":"joe@cool.com"}]}', 'The property name is required'];
+        yield 'user, by template' => ['/user/1', '{"data":{"id":1,"name":"joe","email":"joe@cool.com"}}', null];
+        yield 'user mismatch, by template' => ['/user/1', '{"data":{"id":1,"name":"joe"}}', 'The property email is required'];
+        yield 'not in the specification' => ['/nope', 'anything', null];
+    }
+
+    protected function send(callable $send, string $body, ?string $error): void
+    {
+        if ($error) {
+            $this->expectException(OpenApiSchemaMismatchException::class);
+        }
+
+        try {
+            /** @var ResponseInterface $response */
+            $response = $send();
+        } catch (OpenApiSchemaMismatchException $oasme) {
+            $this->assertStringContainsString($error, (string) $oasme->getErrorSummary());
+
+            throw $oasme;
+        }
+
+        // verifying must leave the body for the caller to read
+        $this->assertSame($body, $response->getBody()->getContents());
+    }
+
+    #[Test]
+    #[DataProvider('responses')]
+    public function guzzleMiddleware(string $path, string $body, ?string $error): void
+    {
+        $stack = HandlerStack::create(new MockHandler([new Response(200, ['Content-Type' => 'application/json'], $body)]));
+        $stack->push(new OpenApiVerifierMiddleware($this->verifier()), 'openapi-verifier');
+        $client = new Client(['handler' => $stack, 'base_uri' => 'http://localhost']);
+
+        $this->send(fn () => $client->get($path), $body, $error);
+    }
+
+    #[Test]
+    #[DataProvider('responses')]
+    public function guzzleMiddlewareAsync(string $path, string $body, ?string $error): void
+    {
+        $stack = HandlerStack::create(new MockHandler([new Response(200, ['Content-Type' => 'application/json'], $body)]));
+        $stack->push(new OpenApiVerifierMiddleware($this->verifier()), 'openapi-verifier');
+        $client = new Client(['handler' => $stack, 'base_uri' => 'http://localhost']);
+
+        $this->send(fn () => $client->getAsync($path)->wait(), $body, $error);
+    }
+
+    #[Test]
+    #[DataProvider('responses')]
+    public function psr18Client(string $path, string $body, ?string $error): void
+    {
+        $inner = new Client(['handler' => HandlerStack::create(new MockHandler([new Response(200, ['Content-Type' => 'application/json'], $body)]))]);
+        $client = new OpenApiVerifyingClient($inner, $this->verifier());
+
+        $this->send(fn () => $client->sendRequest(new Request('GET', 'http://localhost' . $path)), $body, $error);
+    }
+}