Support bearer token

README.md

@@ -38,6 +38,10 @@ CLIENT_PORT=8080 SERVER_PORT=9000 npx @modelcontextprotocol/inspector node build
 
 For more details on ways to use the inspector, see the [Inspector section of the MCP docs site](https://modelcontextprotocol.io/docs/tools/inspector). For help with debugging, see the [Debugging guide](https://modelcontextprotocol.io/docs/tools/debugging).
 
+### Authentication
+
+The inspector supports bearer token authentication for SSE connections. Enter your token in the UI when connecting to an MCP server, and it will be sent in the Authorization header.
+
 ### From this repository
 
 If you're working on the inspector itself:

client/src/App.tsx

@@ -97,6 +97,9 @@ const App = () => {
   >([]);
   const [roots, setRoots] = useState<Root[]>([]);
   const [env, setEnv] = useState<Record<string, string>>({});
+  const [bearerToken, setBearerToken] = useState<string>(() => {
+    return localStorage.getItem("lastBearerToken") || "";
+  });
 
   const [pendingSampleRequests, setPendingSampleRequests] = useState<
     Array<
@@ -160,6 +163,7 @@ const App = () => {
     args,
     sseUrl,
     env,
+    bearerToken,
     proxyServerUrl: PROXY_SERVER_URL,
     onNotification: (notification) => {
       setNotifications((prev) => [...prev, notification as ServerNotification]);
@@ -195,6 +199,10 @@ const App = () => {
     localStorage.setItem("lastTransportType", transportType);
   }, [transportType]);
 
+  useEffect(() => {
+    localStorage.setItem("lastBearerToken", bearerToken);
+  }, [bearerToken]);
+
   // Auto-connect if serverUrl is provided in URL params (e.g. after OAuth callback)
   useEffect(() => {
     const serverUrl = params.get("serverUrl");
@@ -382,6 +390,8 @@ const App = () => {
         setSseUrl={setSseUrl}
         env={env}
         setEnv={setEnv}
+        bearerToken={bearerToken}
+        setBearerToken={setBearerToken}
         onConnect={connectMcpServer}
         stdErrNotifications={stdErrNotifications}
       />

client/src/components/Sidebar.tsx

@@ -35,6 +35,8 @@ interface SidebarProps {
   setSseUrl: (url: string) => void;
   env: Record<string, string>;
   setEnv: (env: Record<string, string>) => void;
+  bearerToken: string;
+  setBearerToken: (token: string) => void;
   onConnect: () => void;
   stdErrNotifications: StdErrNotification[];
 }
@@ -51,11 +53,14 @@ const Sidebar = ({
   setSseUrl,
   env,
   setEnv,
+  bearerToken,
+  setBearerToken,
   onConnect,
   stdErrNotifications,
 }: SidebarProps) => {
   const [theme, setTheme] = useTheme();
   const [showEnvVars, setShowEnvVars] = useState(false);
+  const [showBearerToken, setShowBearerToken] = useState(false);
   const [shownEnvVars, setShownEnvVars] = useState<Set<string>>(new Set());
 
   return (
@@ -110,6 +115,7 @@ const Sidebar = ({
               </div>
             </>
           ) : (
+            <>
               <div className="space-y-2">
                 <label className="text-sm font-medium">URL</label>
                 <Input
@@ -119,6 +125,33 @@ const Sidebar = ({
                   className="font-mono"
                 />
               </div>
+              <div className="space-y-2">
+                <Button
+                  variant="outline"
+                  onClick={() => setShowBearerToken(!showBearerToken)}
+                  className="flex items-center w-full"
+                >
+                  {showBearerToken ? (
+                    <ChevronDown className="w-4 h-4 mr-2" />
+                  ) : (
+                    <ChevronRight className="w-4 h-4 mr-2" />
+                  )}
+                  Authentication
+                </Button>
+                {showBearerToken && (
+                  <div className="space-y-2">
+                    <label className="text-sm font-medium">Bearer Token</label>
+                    <Input
+                      placeholder="Bearer Token"
+                      value={bearerToken}
+                      onChange={(e) => setBearerToken(e.target.value)}
+                      className="font-mono"
+                      type="password"
+                    />
+                  </div>
+                )}
+              </div>
+            </>
           )}
           {transportType === "stdio" && (
             <div className="space-y-2">

client/src/lib/hooks/useConnection.ts

@@ -37,6 +37,7 @@ interface UseConnectionOptions {
   sseUrl: string;
   env: Record<string, string>;
   proxyServerUrl: string;
+  bearerToken?: string;
   requestTimeout?: number;
   onNotification?: (notification: Notification) => void;
   onStdErrNotification?: (notification: Notification) => void;
@@ -57,6 +58,7 @@ export function useConnection({
   sseUrl,
   env,
   proxyServerUrl,
+  bearerToken,
   requestTimeout = DEFAULT_REQUEST_TIMEOUT_MSEC,
   onNotification,
   onStdErrNotification,
@@ -228,9 +230,11 @@ export function useConnection({
       // Inject auth manually instead of using SSEClientTransport, because we're
       // proxying through the inspector server first.
       const headers: HeadersInit = {};
-      const tokens = await authProvider.tokens();
-      if (tokens) {
-        headers["Authorization"] = `Bearer ${tokens.access_token}`;
+
+      // Use manually provided bearer token if available, otherwise use OAuth tokens
+      const token = bearerToken || (await authProvider.tokens())?.access_token;
+      if (token) {
+        headers["Authorization"] = `Bearer ${token}`;
       }
 
       const clientTransport = new SSEClientTransport(backendUrl, {