diff --git a/src/Client.php b/src/Client.php
index 37659eb..2f0f367 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -37,6 +37,19 @@ class Client
     private array $retryStatusCodes = [500, 503];
     private mixed $jsonEncodeFlags;
 
+    protected string $baseUrl = '';
+
+    public function setBaseUrl(string $baseUrl): self
+    {
+        $this->baseUrl = $baseUrl;
+        return $this;
+    }
+
+    public function getBaseUrl(): string
+    {
+        return $this->baseUrl;
+    }
+
     /**
      * @param string $key
      * @param string $value
@@ -127,7 +140,7 @@ public function setMaxRetries(int $maxRetries): self
      *
      * @param array<int> $flags
      * @return self
-    */
+     */
     public function setJsonEncodeFlags(array $flags): self
     {
         $this->jsonEncodeFlags = implode('|', $flags);
@@ -248,6 +261,10 @@ public function fetch(
         ?int $timeoutMs = null,
         ?int $connectTimeoutMs = null,
     ): Response {
+        if (!empty($this->baseUrl) && !preg_match('~^https?://~i', $url)) {
+            $url = rtrim($this->baseUrl, '/') . '/' . ltrim($url, '/');
+        }
+
         if (!in_array($method, [self::METHOD_PATCH, self::METHOD_GET, self::METHOD_CONNECT, self::METHOD_DELETE, self::METHOD_POST, self::METHOD_HEAD, self::METHOD_OPTIONS, self::METHOD_PUT, self::METHOD_TRACE])) {
             throw new Exception("Unsupported HTTP method");
         }
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 028670e..989274e 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -271,6 +271,141 @@ public function testSetGetUserAgent(): void
         $this->assertEquals($userAgent, $client->getUserAgent());
     }
 
+    /**
+     * Test setting and getting the base URL.
+     * @return void
+     */
+    public function testSetGetBaseUrl(): void
+    {
+        $client = new Client();
+        $baseUrl = "http://localhost:8000";
+
+        $client->setBaseUrl($baseUrl);
+
+        $this->assertEquals($baseUrl, $client->getBaseUrl());
+    }
+
+    /**
+     * Test base URL prepending to relative URLs.
+     * @return void
+     */
+    public function testBaseUrlWithRelativePath(): void
+    {
+        $client = new Client();
+        $client->setBaseUrl('http://localhost:8000');
+
+        $resp = $client->fetch(
+            url: '',
+            method: Client::METHOD_GET
+        );
+
+        if ($resp->getStatusCode() === 200) {
+            $respData = $resp->json();
+            $this->assertEquals($respData['method'], Client::METHOD_GET);
+            $this->assertEquals($respData['url'], 'localhost:8000');
+        } else {
+            echo "Please configure your PHP inbuilt SERVER";
+        }
+    }
+
+    /**
+     * Test base URL with path appending.
+     * @return void
+     */
+    public function testBaseUrlWithPath(): void
+    {
+        $client = new Client();
+        $client->setBaseUrl('http://localhost:8000');
+
+        $resp = $client->fetch(
+            url: 'redirect',
+            method: Client::METHOD_GET
+        );
+
+        if ($resp->getStatusCode() === 200) {
+            $respData = $resp->json();
+            $this->assertEquals($respData['page'], "redirectedPage");
+        } else {
+            echo "Please configure your PHP inbuilt SERVER";
+        }
+    }
+
+    /**
+     * Test base URL doesn't interfere with absolute URLs.
+     * @return void
+     */
+    public function testBaseUrlWithAbsoluteUrl(): void
+    {
+        $client = new Client();
+        $client->setBaseUrl('http://example.com');
+
+        $resp = $client->fetch(
+            url: 'http://localhost:8000',
+            method: Client::METHOD_GET
+        );
+
+        if ($resp->getStatusCode() === 200) {
+            $respData = $resp->json();
+            $this->assertEquals($respData['method'], Client::METHOD_GET);
+            $this->assertEquals($respData['url'], 'localhost:8000');
+        } else {
+            echo "Please configure your PHP inbuilt SERVER";
+        }
+    }
+
+    /**
+     * Test base URL with query parameters.
+     * @return void
+     */
+    public function testBaseUrlWithQuery(): void
+    {
+        $client = new Client();
+        $client->setBaseUrl('http://localhost:8000');
+
+        $resp = $client->fetch(
+            url: '',
+            method: Client::METHOD_GET,
+            query: [
+                'name' => 'John Doe',
+                'age' => '30',
+            ]
+        );
+
+        if ($resp->getStatusCode() === 200) {
+            $respData = $resp->json();
+            $this->assertEquals($respData['method'], Client::METHOD_GET);
+            $this->assertEquals(
+                json_encode($respData['query']),
+                json_encode(['name' => 'John Doe', 'age' => '30'])
+            );
+        } else {
+            echo "Please configure your PHP inbuilt SERVER";
+        }
+    }
+
+    /**
+     * Test base URL with trailing slash normalization.
+     * @return void
+     */
+    public function testBaseUrlTrailingSlashNormalization(): void
+    {
+        $client = new Client();
+
+        // Test with trailing slash in base URL
+        $client->setBaseUrl('http://localhost:8000/');
+        $resp = $client->fetch(
+            url: '/redirect',
+            method: Client::METHOD_GET
+        );
+
+        if ($resp->getStatusCode() === 200) {
+            $respData = $resp->json();
+            $this->assertEquals($respData['page'], "redirectedPage");
+        } else {
+            echo "Please configure your PHP inbuilt SERVER";
+        }
+    }
+
     /**
      * Data provider for testFetch
      * @return array<string, array<mixed>>