feat: support custom header

client/src/components/Sidebar.tsx

@@ -14,6 +14,9 @@ import {
   RefreshCwOff,
   Copy,
   CheckCheck,
+  Hash,
+  Plus,
+  Minus,
 } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
@@ -97,6 +100,7 @@ const Sidebar = ({
   const [showEnvVars, setShowEnvVars] = useState(false);
   const [showBearerToken, setShowBearerToken] = useState(false);
   const [showConfig, setShowConfig] = useState(false);
+  const [showHeaders, setShowHeaders] = useState(false);
   const [shownEnvVars, setShownEnvVars] = useState<Set<string>>(new Set());
   const [copiedServerEntry, setCopiedServerEntry] = useState(false);
   const [copiedServerFile, setCopiedServerFile] = useState(false);
@@ -620,6 +624,109 @@ const Sidebar = ({
             )}
           </div>
 
+          {/* Headers */}
+          <div className="space-y-2">
+            <Button
+              variant="outline"
+              onClick={() => setShowHeaders(!showHeaders)}
+              className="flex items-center w-full"
+              data-testid="headers-button"
+              aria-expanded={showHeaders}
+            >
+              {showHeaders ? (
+                <ChevronDown className="w-4 h-4 mr-2" />
+              ) : (
+                <ChevronRight className="w-4 h-4 mr-2" />
+              )}
+              <Hash className="w-4 h-4 mr-2" />
+              Headers
+            </Button>
+            {showHeaders && (
+              <div className="space-y-2">
+                {(() => {
+                  const headersJson = config.MCP_CUSTOM_HEADERS?.value as string || "[]";
+                  let headers: Array<{ name: string; value: string }> = [];
+
+                  try {
+                    headers = JSON.parse(headersJson);
+                  } catch {
+                    headers = [];
+                  }
+
+                  const updateHeaders = (newHeaders: Array<{ name: string; value: string }>) => {
+                    const newConfig = { ...config };
+                    newConfig.MCP_CUSTOM_HEADERS = {
+                      ...config.MCP_CUSTOM_HEADERS,
+                      value: JSON.stringify(newHeaders),
+                    };
+                    setConfig(newConfig);
+                  };
+
+                  const addHeader = () => {
+                    updateHeaders([...headers, { name: "", value: "" }]);
+                  };
+
+                  const removeHeader = (index: number) => {
+                    const newHeaders = headers.filter((_, i) => i !== index);
+                    updateHeaders(newHeaders);
+                  };
+
+                  const updateHeader = (index: number, field: "name" | "value", value: string) => {
+                    const newHeaders = [...headers];
+                    newHeaders[index] = { ...newHeaders[index], [field]: value };
+                    updateHeaders(newHeaders);
+                  };
+
+                  return (
+                    <>
+                      {headers.map((header, index) => (
+                        <div key={index} className="space-y-2 p-2 border rounded">
+                          <div className="flex items-center justify-between">
+                            <label className="text-sm font-medium text-green-600">
+                              Header {index + 1}
+                            </label>
+                            <Button
+                              variant="outline"
+                              size="sm"
+                              onClick={() => removeHeader(index)}
+                              data-testid={`remove-header-${index}`}
+                            >
+                              <Minus className="h-4 w-4" />
+                            </Button>
+                          </div>
+                          <Input
+                            placeholder="Header name (e.g., X-API-Key)"
+                            value={header.name}
+                            onChange={(e) => updateHeader(index, "name", e.target.value)}
+                            data-testid={`header-name-${index}`}
+                            className="font-mono"
+                          />
+                          <Input
+                            placeholder="Header value"
+                            value={header.value}
+                            onChange={(e) => updateHeader(index, "value", e.target.value)}
+                            data-testid={`header-value-${index}`}
+                            className="font-mono"
+                            type="password"
+                          />
+                        </div>
+                      ))}
+                      <Button
+                        variant="outline"
+                        onClick={addHeader}
+                        className="w-full"
+                        data-testid="add-header-button"
+                      >
+                        <Plus className="h-4 w-4 mr-2" />
+                        Add Header
+                      </Button>
+                    </>
+                  );
+                })()}
+              </div>
+            )}
+          </div>
+
           <div className="space-y-2">
             {connectionStatus === "connected" && (
               <div className="grid grid-cols-2 gap-4">

client/src/components/__tests__/Sidebar.test.tsx

@@ -648,6 +648,144 @@ describe("Sidebar Environment Variables", () => {
     });
   });
 
+  describe("Headers Operations", () => {
+    const openHeadersSection = () => {
+      const button = screen.getByTestId("headers-button");
+      fireEvent.click(button);
+    };
+
+    it("should add a new header", () => {
+      const setConfig = jest.fn();
+      renderSidebar({ config: DEFAULT_INSPECTOR_CONFIG, setConfig });
+
+      openHeadersSection();
+
+      const addButton = screen.getByTestId("add-header-button");
+      fireEvent.click(addButton);
+
+      expect(setConfig).toHaveBeenCalledWith(
+        expect.objectContaining({
+          MCP_CUSTOM_HEADERS: {
+            label: "Custom Headers",
+            description: "Custom headers for authentication with the MCP server (stored as JSON array)",
+            value: '[{"name":"","value":""}]',
+            is_session_item: true,
+          },
+        }),
+      );
+    });
+
+    it("should update header name", () => {
+      const setConfig = jest.fn();
+      const config = {
+        ...DEFAULT_INSPECTOR_CONFIG,
+        MCP_CUSTOM_HEADERS: {
+          ...DEFAULT_INSPECTOR_CONFIG.MCP_CUSTOM_HEADERS,
+          value: '[{"name":"","value":""}]',
+        },
+      };
+
+      renderSidebar({ config, setConfig });
+
+      openHeadersSection();
+
+      const headerNameInput = screen.getByTestId("header-name-0");
+
+      fireEvent.change(headerNameInput, { target: { value: "X-API-Key" } });
+
+      expect(setConfig).toHaveBeenCalledWith(
+        expect.objectContaining({
+          MCP_CUSTOM_HEADERS: {
+            label: "Custom Headers",
+            description: "Custom headers for authentication with the MCP server (stored as JSON array)",
+            value: '[{"name":"X-API-Key","value":""}]',
+            is_session_item: true,
+          },
+        }),
+      );
+    });
+
+    it("should update header value", () => {
+      const setConfig = jest.fn();
+      const config = {
+        ...DEFAULT_INSPECTOR_CONFIG,
+        MCP_CUSTOM_HEADERS: {
+          ...DEFAULT_INSPECTOR_CONFIG.MCP_CUSTOM_HEADERS,
+          value: '[{"name":"","value":""}]',
+        },
+      };
+
+      renderSidebar({ config, setConfig });
+
+      openHeadersSection();
+
+      const headerValueInput = screen.getByTestId("header-value-0");
+
+      fireEvent.change(headerValueInput, { target: { value: "secret-key-123" } });
+
+      expect(setConfig).toHaveBeenCalledWith(
+        expect.objectContaining({
+          MCP_CUSTOM_HEADERS: {
+            label: "Custom Headers",
+            description: "Custom headers for authentication with the MCP server (stored as JSON array)",
+            value: '[{"name":"","value":"secret-key-123"}]',
+            is_session_item: true,
+          },
+        }),
+      );
+    });
+
+    it("should remove a header", () => {
+      const setConfig = jest.fn();
+      const config = {
+        ...DEFAULT_INSPECTOR_CONFIG,
+        MCP_CUSTOM_HEADERS: {
+          ...DEFAULT_INSPECTOR_CONFIG.MCP_CUSTOM_HEADERS,
+          value: '[{"name":"X-API-Key","value":"secret-key-123"}]',
+        },
+      };
+
+      renderSidebar({ config, setConfig });
+
+      openHeadersSection();
+
+      const removeButton = screen.getByTestId("remove-header-0");
+      fireEvent.click(removeButton);
+
+      expect(setConfig).toHaveBeenCalledWith(
+        expect.objectContaining({
+          MCP_CUSTOM_HEADERS: {
+            label: "Custom Headers",
+            description: "Custom headers for authentication with the MCP server (stored as JSON array)",
+            value: "[]",
+            is_session_item: true,
+          },
+        }),
+      );
+    });
+
+    it("should handle multiple headers", () => {
+      const setConfig = jest.fn();
+      const config = {
+        ...DEFAULT_INSPECTOR_CONFIG,
+        MCP_CUSTOM_HEADERS: {
+          ...DEFAULT_INSPECTOR_CONFIG.MCP_CUSTOM_HEADERS,
+          value: '[{"name":"X-API-Key","value":"key1"},{"name":"Authorization","value":"Bearer token"}]',
+        },
+      };
+
+      renderSidebar({ config, setConfig });
+
+      openHeadersSection();
+
+      // Verify both headers are displayed
+      expect(screen.getByTestId("header-name-0")).toHaveValue("X-API-Key");
+      expect(screen.getByTestId("header-value-0")).toHaveValue("key1");
+      expect(screen.getByTestId("header-name-1")).toHaveValue("Authorization");
+      expect(screen.getByTestId("header-value-1")).toHaveValue("Bearer token");
+    });
+  });
+
   describe("Copy Configuration Features", () => {
     beforeEach(() => {
       jest.clearAllMocks();

client/src/lib/configurationTypes.ts

@@ -39,4 +39,9 @@ export type InspectorConfig = {
    * Session token for authenticating with the MCP Proxy Server. This token is displayed in the proxy server console on startup.
    */
   MCP_PROXY_AUTH_TOKEN: ConfigItem;
+
+  /**
+   * Custom headers for authentication with the MCP server. JSON string containing array of {name, value} objects.
+   */
+  MCP_CUSTOM_HEADERS: ConfigItem;
 };

client/src/lib/constants.ts

@@ -65,4 +65,10 @@ export const DEFAULT_INSPECTOR_CONFIG: InspectorConfig = {
     value: "",
     is_session_item: true,
   },
+  MCP_CUSTOM_HEADERS: {
+    label: "Custom Headers",
+    description: "Custom headers for authentication with the MCP server (stored as JSON array)",
+    value: "[]",
+    is_session_item: true,
+  },
 } as const;

client/src/lib/hooks/useConnection.ts

@@ -320,7 +320,32 @@ export function useConnection({
       // Use manually provided bearer token if available, otherwise use OAuth tokens
       const token =
         bearerToken || (await serverAuthProvider.tokens())?.access_token;
+
+      // Check for custom headers from configuration
+      const customHeadersJson = config.MCP_CUSTOM_HEADERS?.value as string;
+      let customHeaders: Array<{ name: string; value: string }> = [];
+
+      try {
+        if (customHeadersJson) {
+          customHeaders = JSON.parse(customHeadersJson);
+        }
+      } catch (error) {
+        console.warn("Failed to parse custom headers:", error);
+      }
+
+      if (customHeaders.length > 0) {
+        // Use custom headers from configuration
+        // Send headers with x-mcp-custom- prefix so server can identify them
+        customHeaders.forEach(({ name, value }) => {
+          if (name && value) {
+            const headerKey = `x-mcp-custom-${name.toLowerCase()}`;
+            headers[headerKey] = value;
+          }
+        });
+      }
+
       if (token) {
+        // Fallback to bearer token with header name
         const authHeaderName = headerName || "Authorization";
 
         // Add custom header name as a special request header to let the server know which header to pass through
@@ -346,6 +371,7 @@ export function useConnection({
         | SSEClientTransportOptions;
 
       let mcpProxyServerUrl;
+
       switch (transportType) {
         case "stdio":
           mcpProxyServerUrl = new URL(`${getMCPProxyAddress(config)}/stdio`);

server/src/index.ts

@@ -77,6 +77,20 @@ const getHttpHeaders = (
       headers[customHeaderName] = value as string;
     }
   }
+
+  // Handle multiple custom headers sent by the new client implementation
+  // Look for headers that start with 'x-mcp-custom-' prefix
+  Object.keys(req.headers).forEach((headerName) => {
+    if (headerName.startsWith('x-mcp-custom-')) {
+      // Extract the actual header name from x-mcp-custom-[actual-header-name]
+      const actualHeaderName = headerName.substring('x-mcp-custom-'.length);
+      const headerValue = req.headers[headerName];
+      const value = Array.isArray(headerValue) ? headerValue[headerValue.length - 1] : headerValue;
+      if (value) {
+        headers[actualHeaderName] = value;
+      }
+    }
+  });
   return headers;
 };