diff --git a/ProcessIndieAuth.module.php b/ProcessIndieAuth.module.php
index 9295b58..e498eeb 100644
--- a/ProcessIndieAuth.module.php
+++ b/ProcessIndieAuth.module.php
@@ -926,9 +926,9 @@ public function authorizationEndpoint(): void
 
             $request['client_id'] = Server::canonizeUrl($request['client_id']);
             $request['redirect_uri'] = Server::canonizeUrl($request['redirect_uri']);
-            $client = $this->getClientInfo($request['client_id']);
+            $client = Server::getClientInfo($request['client_id']);
 
-            if (!Server::isRedirectUriAllowed($request['redirect_uri'], $request['client_id'], $client['redirect_uri'])) {
+            if (!Server::isRedirectUriAllowed($request['redirect_uri'], $request['client_id'], $client['redirect_uris'])) {
                 $this->httpResponse('mismatched redirect_uri');
             }
 
@@ -2038,6 +2038,11 @@ private function httpResponse($response, int $http_status = 400, array $headers
         exit;
     }
 
+    /**
+     * DEPRECATED
+     *
+     * @see Client::getInfo()
+     */
     private function getClientInfo(string $url): array
     {
         $info = array_fill_keys([
diff --git a/src/IndieAuth/Server.php b/src/IndieAuth/Server.php
index 0cbafd1..d733c47 100644
--- a/src/IndieAuth/Server.php
+++ b/src/IndieAuth/Server.php
@@ -11,8 +11,81 @@
 
 namespace IndieAuth;
 
-final class Server 
+use IndieAuth\Libs\{
+    Barnabywalters\Mf2 as Mf2Helper,
+    Mf2
+};
+use ProcessWire\WireHttp;
+
+final class Server
 {
+    /**
+     * Get client information
+     * First check if the client_id itself is the info (JSON)
+     * Fallback to checking for h-app or h-x-app
+     *
+     * @see https://github.com/indieweb/indieauth/issues/133
+     */
+    public static function getClientInfo(string $client_id): array
+    {
+        $headers = static::fetchHead($client_id, ['content-type']);
+
+        $is_json = false;
+        if ($headers) {
+            if (static::hasContentType('application/json', $headers['content-type'])) {
+                $is_json = true;
+            }
+        }
+
+        $content = static::fetchBody($client_id);
+
+        if ($is_json) {
+            $json = json_decode($content, true);
+            if ($json) {
+                return [
+                    'name' => $json['client_name'] ?? '',
+                    'url' => $json['client_uri'] ?? '',
+                    'logo' => $json['logo_uri'] ?? '',
+                    'redirect_uris' => $json['redirect_uris'] ?? [],
+                ];
+            }
+        }
+
+        $info = array_fill_keys([
+            'name',
+            'url',
+            'logo',
+        ], '');
+
+        $info['name'] = parse_url($client_id, PHP_URL_HOST);
+        $info['url'] = $client_id;
+        $info['redirect_uris'] = [];
+
+        $mf2 = Mf2\parse($content, $client_id);
+        $info['redirect_uris'] = $mf2['rels']['redirect_uri'] ?? [];
+
+        $apps = Mf2Helper\findMicroformatsByType($mf2, 'h-app');
+        if (!$apps) {
+            $apps = Mf2Helper\findMicroformatsByType($mf2, 'h-x-app');
+        }
+
+        if (!$apps) {
+            return $info;
+        }
+
+        $app = reset($apps);
+
+        if (Mf2Helper\hasProp($app, 'name')) {
+            $info['name'] = Mf2Helper\getPlaintext($app, 'name');
+        }
+
+        if (Mf2Helper\hasProp($app, 'logo')) {
+            $info['logo'] = Mf2Helper\getPlaintext($app, 'logo');
+        }
+
+        return $info;
+    }
+
     /**
      * @see https://indieauth.spec.indieweb.org/#client-identifier
      */
@@ -169,5 +242,66 @@ public static function base64UrlEncode(string $input): string
     {
         return rtrim(strtr(base64_encode($input), '+/', '-_'), '=');
     }
+
+    /**
+     * Perform a HEAD request and return an array of headers
+     * If $requested_headers is provided, only return those headers.
+     * For example, `$requested_headers = ['link']` will return
+     * only the Link: headers
+     */
+    private static function fetchHead(
+        string $url,
+        array $requested_headers = []
+    ): ?array {
+        $http = new WireHttp();
+
+        $response = $http->status($url);
+        if (!$response) {
+            return null;
+        }
+
+        $http_headers = $http->getResponseHeaderValues('', true);
+
+        if ($requested_headers) {
+            $http_headers = array_intersect_key(
+                $http_headers,
+                array_fill_keys($requested_headers, [])
+            );
+
+            if (!$http_headers) {
+                return null;
+            }
+        }
+
+        return $http_headers;
+    }
+
+    /**
+     * Fetch the content of a URL
+     */
+    private static function fetchBody(string $url): string
+    {
+        $http = new WireHttp();
+        $content = $http->get($url);
+
+        if (!$content) {
+            return '';
+        }
+
+        return $content;
+    }
+
+    private static function hasContentType(
+        string $expected,
+        array $content_types
+    ) {
+        foreach ($content_types as $content_type) {
+            if (stripos($content_type, $expected) !== false) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }