feat: support --allowedOrigins & --blockedOrigins in CLI

README.md

@@ -268,6 +268,14 @@ The Chrome DevTools MCP server supports the following configuration option:
   Path to a file to write debug logs to. Set the env variable `DEBUG` to `*` to enable verbose logs. Useful for submitting bug reports.
   - **Type:** string
 
+- **`--allowedOrigins`**
+  Semicolon-separated list of origins the browser is allowed to request. If not specified, all origins are allowed (except those in blockedOrigins). Example: https://example.com;https://api.example.com
+  - **Type:** string
+
+- **`--blockedOrigins`**
+  Semicolon-separated list of origins the browser is blocked from requesting. Takes precedence over allowedOrigins. Example: https://ads.example.com;https://tracker.example.com
+  - **Type:** string
+
 <!-- END AUTO GENERATED OPTIONS -->
 
 Pass them via the `args` property in the JSON configuration. For example:

package.json

@@ -41,7 +41,8 @@
     "core-js": "3.45.1",
     "debug": "4.4.3",
     "puppeteer-core": "24.22.3",
-    "yargs": "18.0.0"
+    "yargs": "18.0.0",
+    "zod": "3.24.1"
   },
   "devDependencies": {
     "@eslint/js": "^9.35.0",

src/McpContext.ts

@@ -25,6 +25,7 @@ import {takeSnapshot} from './tools/snapshot.js';
 import {CLOSE_PAGE_ERROR} from './tools/ToolDefinition.js';
 import type {Context} from './tools/ToolDefinition.js';
 import type {TraceResult} from './trace-processing/parse.js';
+import type {UrlValidator} from './utils/urlValidator.js';
 import {WaitForHelper} from './WaitForHelper.js';
 
 export interface TextSnapshotNode extends SerializedAXNode {
@@ -77,10 +78,16 @@ export class McpContext implements Context {
 
   #nextSnapshotId = 1;
   #traceResults: TraceResult[] = [];
+  #urlValidator?: UrlValidator;
 
-  private constructor(browser: Browser, logger: Debugger) {
+  private constructor(
+    browser: Browser,
+    logger: Debugger,
+    urlValidator?: UrlValidator,
+  ) {
     this.browser = browser;
     this.logger = logger;
+    this.#urlValidator = urlValidator;
 
     this.#networkCollector = new NetworkCollector(
       this.browser,
@@ -109,10 +116,52 @@ export class McpContext implements Context {
     this.setSelectedPageIdx(0);
     await this.#networkCollector.init();
     await this.#consoleCollector.init();
+    if (this.#urlValidator?.hasRestrictions()) {
+      await this.#setupRequestInterception();
+    }
+  }
+
+  async #setupRequestInterception() {
+    const pages = await this.browser.pages();
+    for (const page of pages) {
+      await this.#enableRequestInterceptionForPage(page);
+    }
+
+    this.browser.on('targetcreated', async target => {
+      const page = await target.page();
+      if (page) {
+        await this.#enableRequestInterceptionForPage(page);
+      }
+    });
   }
 
-  static async from(browser: Browser, logger: Debugger) {
-    const context = new McpContext(browser, logger);
+  async #enableRequestInterceptionForPage(page: Page) {
+    try {
+      await page.setRequestInterception(true);
+
+      page.on('request', interceptedRequest => {
+        if (interceptedRequest.isInterceptResolutionHandled()) {
+          return;
+        }
+
+        const url = interceptedRequest.url();
+        if (this.#urlValidator && !this.#urlValidator.isAllowed(url)) {
+          void interceptedRequest.abort('blockedbyclient', 0);
+        } else {
+          void interceptedRequest.continue({}, 0);
+        }
+      });
+    } catch (error) {
+      this.logger(`Failed to enable request interception for page: ${error}`);
+    }
+  }
+
+  static async from(
+    browser: Browser,
+    logger: Debugger,
+    urlValidator?: UrlValidator,
+  ) {
+    const context = new McpContext(browser, logger, urlValidator);
     await context.#init();
     return context;
   }
@@ -133,6 +182,9 @@ export class McpContext implements Context {
     this.setSelectedPageIdx(pages.indexOf(page));
     this.#networkCollector.addPage(page);
     this.#consoleCollector.addPage(page);
+    if (this.#urlValidator?.hasRestrictions()) {
+      await this.#enableRequestInterceptionForPage(page);
+    }
     return page;
   }
   async closePage(pageIdx: number): Promise<void> {

src/cli.ts

@@ -54,6 +54,16 @@ export const cliOptions = {
     describe:
       'Path to a file to write debug logs to. Set the env variable `DEBUG` to `*` to enable verbose logs. Useful for submitting bug reports.',
   },
+  allowedOrigins: {
+    type: 'string' as const,
+    describe:
+      'Semicolon-separated list of origins the browser is allowed to request. If not specified, all origins are allowed (except those in blockedOrigins). Example: https://example.com;https://api.example.com',
+  },
+  blockedOrigins: {
+    type: 'string' as const,
+    describe:
+      'Semicolon-separated list of origins the browser is blocked from requesting. Takes precedence over allowedOrigins. Example: https://ads.example.com;https://tracker.example.com',
+  },
 };
 
 export function parseArguments(version: string, argv = process.argv) {
@@ -78,6 +88,14 @@ export function parseArguments(version: string, argv = process.argv) {
       ['$0 --channel dev', 'Use Chrome Dev installed on this system'],
       ['$0 --channel stable', 'Use stable Chrome installed on this system'],
       ['$0 --logFile /tmp/log.txt', 'Save logs to a file'],
+      [
+        '$0 --allowedOrigins "https://example.com;https://api.example.com"',
+        'Only allow requests to specific origins',
+      ],
+      [
+        '$0 --blockedOrigins "https://ads.example.com;https://tracker.com"',
+        'Block requests to specific origins',
+      ],
       ['$0 --help', 'Print CLI options'],
     ]);
 

src/main.ts

@@ -32,6 +32,7 @@ import * as screenshotTools from './tools/screenshot.js';
 import * as scriptTools from './tools/script.js';
 import * as snapshotTools from './tools/snapshot.js';
 import type {ToolDefinition} from './tools/ToolDefinition.js';
+import {UrlValidator} from './utils/urlValidator.js';
 
 function readPackageJson(): {version?: string} {
   const currentDir = import.meta.dirname;
@@ -55,6 +56,14 @@ export const args = parseArguments(version);
 const logFile = args.logFile ? saveLogsToFile(args.logFile) : undefined;
 
 logger(`Starting Chrome DevTools MCP Server v${version}`);
+
+const allowedOrigins = UrlValidator.parseOrigins(args.allowedOrigins);
+const blockedOrigins = UrlValidator.parseOrigins(args.blockedOrigins);
+const urlValidator =
+  allowedOrigins.length > 0 || blockedOrigins.length > 0
+    ? new UrlValidator({allowedOrigins, blockedOrigins}, logger)
+    : undefined;
+
 const server = new McpServer(
   {
     name: 'chrome_devtools',
@@ -79,7 +88,7 @@ async function getContext(): Promise<McpContext> {
     logFile,
   });
   if (context?.browser !== browser) {
-    context = await McpContext.from(browser, logger);
+    context = await McpContext.from(browser, logger, urlValidator);
   }
   return context;
 }

src/utils/urlValidator.ts

@@ -0,0 +1,117 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type {Debugger} from 'debug';
+
+export class UrlValidator {
+  #allowedOrigins: string[];
+  #blockedOrigins: string[];
+  #logger: Debugger;
+
+  constructor(
+    options: {
+      allowedOrigins?: string[];
+      blockedOrigins?: string[];
+    },
+    logger: Debugger,
+  ) {
+    this.#allowedOrigins = options.allowedOrigins ?? [];
+    this.#blockedOrigins = options.blockedOrigins ?? [];
+    this.#logger = logger;
+
+    if (this.#allowedOrigins.length > 0) {
+      this.#logger(
+        `URL validation enabled. Allowed origins: ${this.#allowedOrigins.join(', ')}`,
+      );
+    }
+    if (this.#blockedOrigins.length > 0) {
+      this.#logger(
+        `URL validation enabled. Blocked origins: ${this.#blockedOrigins.join(', ')}`,
+      );
+    }
+  }
+
+  static parseOrigins(originsString?: string): string[] {
+    if (!originsString) {
+      return [];
+    }
+    return originsString
+      .split(';')
+      .map(o => o.trim())
+      .filter(o => o.length > 0);
+  }
+
+  isAllowed(url: string): boolean {
+    if (this.#isSpecialUrl(url)) {
+      return true;
+    }
+
+    try {
+      const origin = new URL(url).origin;
+
+      if (this.#matchesAnyOrigin(origin, this.#blockedOrigins)) {
+        this.#logger(`Blocked request to ${url} (origin: ${origin})`);
+        return false;
+      }
+
+      if (this.#allowedOrigins.length === 0) {
+        return true;
+      }
+
+      const allowed = this.#matchesAnyOrigin(origin, this.#allowedOrigins);
+      if (!allowed) {
+        this.#logger(
+          `Blocked request to ${url} (origin: ${origin} not in allowlist)`,
+        );
+      }
+      return allowed;
+    } catch {
+      return true;
+    }
+  }
+
+  #isSpecialUrl(url: string): boolean {
+    const lowerUrl = url.toLowerCase();
+    return (
+      lowerUrl.startsWith('about:') ||
+      lowerUrl.startsWith('data:') ||
+      lowerUrl.startsWith('blob:') ||
+      lowerUrl.startsWith('file:')
+    );
+  }
+
+  #matchesAnyOrigin(origin: string, patterns: string[]): boolean {
+    for (const pattern of patterns) {
+      if (this.#matchesOriginPattern(origin, pattern)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  #matchesOriginPattern(origin: string, pattern: string): boolean {
+    if (origin === pattern) {
+      return true;
+    }
+
+    if (pattern.includes('*')) {
+      const regex = this.#patternToRegex(pattern);
+      return regex.test(origin);
+    }
+
+    return false;
+  }
+
+  #patternToRegex(pattern: string): RegExp {
+    const escaped = pattern.replace(/[.+?^${}()|[\]\\]/g, '\\$&');
+    const regexPattern = escaped.replace(/\*/g, '[^\\/]+');
+    return new RegExp(`^${regexPattern}$`);
+  }
+
+  hasRestrictions(): boolean {
+    return this.#allowedOrigins.length > 0 || this.#blockedOrigins.length > 0;
+  }
+}

tests/utils.ts

@@ -4,13 +4,18 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 import logger from 'debug';
+import type {Debugger} from 'debug';
 import type {Browser} from 'puppeteer';
 import puppeteer from 'puppeteer';
 import type {HTTPRequest, HTTPResponse} from 'puppeteer-core';
 
 import {McpContext} from '../src/McpContext.js';
 import {McpResponse} from '../src/McpResponse.js';
 
+export function createLogger(namespace = 'test'): Debugger {
+  return logger(namespace);
+}
+
 let browser: Browser | undefined;
 
 export async function withBrowser(