ManagedCode.Playwright.Stealth (.NET)

ManagedCode.Playwright.Stealth applies a curated set of init scripts to Microsoft.Playwright contexts to reduce common bot-detection signals. It adapts the original playwright_stealth scripts for .NET with ManagedCode conventions.

Install

dotnet add package ManagedCode.Playwright.Stealth

Quick Start

using Microsoft.Playwright;
using ManagedCode.Playwright.Stealth;

using var playwright = await Playwright.CreateAsync();

// One-call launch with stealth args + context pre-configured:
var (browser, context) = await playwright.Chromium.LaunchStealthAsync();

var page = await context.NewPageAsync();
await page.GotoAsync("https://www.browserscan.net/bot-detection");

Manual Setup

If you need more control over launch options:

using var playwright = await Playwright.CreateAsync();
await using var browser = await playwright.Chromium.LaunchAsync(new BrowserTypeLaunchOptions
{
    Headless = true,
    Args = PlaywrightStealthExtensions.StealthArgs // recommended Chrome flags
});

var context = await browser.NewContextAsync();

// Apply stealth before creating pages.
await context.ApplyStealthAsync();

var page = await context.NewPageAsync();
await page.GotoAsync("https://www.browserscan.net/bot-detection");

Configuration

var config = new StealthConfig
{
    NavigatorHardwareConcurrency = 8,
    NavigatorDeviceMemory = 16,
    NavigatorMaxTouchPoints = 1,
    NavigatorUserAgentValue = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36",
    Vendor = "Intel Inc.",
    Renderer = "Intel Iris OpenGL Engine"
};

await context.ApplyStealthAsync(config);

Apply stealth on a page (if you already have a page instance):

var page = await context.NewPageAsync();
await page.ApplyStealthAsync();
await page.GotoAsync("https://www.browserscan.net/bot-detection");

Disable individual patches:

var config = new StealthConfig
{
    WebDriver = false,
    WebglVendor = false,
    CanvasFingerprint = false,
    AudioContext = false,
    PerformanceJitter = false
};

await context.ApplyStealthAsync(config);

Patched Signals

The configuration can patch 31 detection vectors across these categories. Defaults preserve native navigator values where current Chromium already exposes a normal value.

Navigator Properties

Patch	Description	Config
navigator.webdriver	Returns false instead of true	WebDriver
navigator.plugins / mimeTypes	Fake plugin array (Chrome PDF Plugin, etc.)	NavigatorPlugins
navigator.languages	Preserves native values by default; configurable language array when supplied	NavigatorLanguages
navigator.userAgent	Strips headless markers from UA string	NavigatorUserAgent
navigator.vendor	Preserves native value when already "Google Inc."; configurable otherwise	NavigatorVendor
navigator.platform	Configurable platform string	NavigatorPlatform
navigator.hardwareConcurrency	Preserves native value by default; configurable CPU core count when supplied	NavigatorHardwareConcurrency
navigator.deviceMemory	Preserves native value by default; configurable device memory in GB when supplied	NavigatorDeviceMemory
navigator.connection	Preserves native value when present; mocks NetworkInformation when missing	NavigatorConnection
navigator.permissions	Normalizes Notification permission state	NavigatorPermissions
navigator.maxTouchPoints	Preserves native value by default; configurable touch point count when supplied	NavigatorMaxTouchPoints
navigator.pdfViewerEnabled	Preserves native value when present; mocks it when missing	NavigatorPdfViewer

Chrome APIs

Patch	Description	Config
window.chrome / chrome.runtime	Full Chrome extension API mock	ChromeRuntime
chrome.app	Chrome App API mock	ChromeApp
chrome.csi	Chrome CSI timing mock	ChromeCsi
chrome.loadTimes	Preserves the native headful API when present; mocks it when missing	ChromeLoadTimes

Graphics & Rendering

Patch	Description	Config
WebGL vendor/renderer	Spoofs UNMASKED and standard WebGL params; hides ANGLE/SwiftShader	WebglVendor
Canvas fingerprint	Adds session-stable noise to canvas rendering	CanvasFingerprint
Broken image dimensions	Fixes 16x16 headless artifact to 0x0	BrokenImage

Audio & Media

Patch	Description	Config
AudioContext fingerprint	Adds noise to audio frequency/channel data	AudioContext
Media codecs	Correct codec support responses	MediaCodecs
Speech synthesis	Mock voice list for getVoices()	SpeechSynthesis

Window & Screen

Patch	Description	Config
window.outerWidth/Height	Realistic outer dimensions	OuterDimensions
screen.* dimensions	Consistent screen width/height/colorDepth	ScreenDimensions

Anti-Detection & Timing

Patch	Description	Config
CDP detection	Masks Chrome DevTools Protocol traces	CdpDetection
Automation properties	Removes cdc_*, $cdc_*, domAutomationController	AutomationProperties
Performance jitter	Adds realistic timing noise to performance.now() and requestAnimationFrame	PerformanceJitter

DOM & Internals

Patch	Description	Config
iframe contentWindow	Fixes iframe proxy behavior	IframeContentWindow
Hairline detection	Fixes Modernizr offsetHeight check	Hairline

Public API

Extension Methods

// Apply to browser context (recommended)
await context.ApplyStealthAsync();
await context.ApplyStealthAsync(customConfig);

// Apply to individual page
await page.ApplyStealthAsync();
await page.ApplyStealthAsync(customConfig);

// One-call launch with stealth pre-configured
var (browser, context) = await playwright.Chromium.LaunchStealthAsync();
var (browser, context) = await playwright.Chromium.LaunchStealthAsync(config, launchOptions, contextOptions);

Stealth Chrome Arguments

// Access recommended Chrome args for manual launch setup
string[] args = PlaywrightStealthExtensions.StealthArgs;

Configuration Reference

Toggle Options (bool)

WebDriver, WebglVendor, ChromeApp, ChromeCsi, ChromeLoadTimes, ChromeRuntime, IframeContentWindow, MediaCodecs, Hairline, OuterDimensions, NavigatorLanguages, NavigatorPermissions, NavigatorPlatform, NavigatorPlugins, NavigatorUserAgent, NavigatorVendor, NavigatorConnection, NavigatorPdfViewer, BrokenImage, SpeechSynthesis, ScreenDimensions, CdpDetection, AutomationProperties, CanvasFingerprint, PerformanceJitter, AudioContext

Numeric Options (int)

• NavigatorHardwareConcurrency (default: 0 to preserve native value, set >0 to spoof)
• NavigatorDeviceMemory (default: 0 to preserve native value, set >0 to spoof)
• NavigatorMaxTouchPoints (default: -1 to preserve native value, set >=0 to spoof)

String Options

• NavigatorUserAgentValue - Custom user agent string
• NavigatorPlatformValue - Custom platform (e.g., "Win32")
• NavigatorVendorValue - Vendor name (default: "Google Inc.")
• Vendor - WebGL vendor (default: "Intel Inc.")
• Renderer - WebGL renderer (default: "Intel Iris OpenGL Engine")
• Languages - Language array (default: empty to preserve native values)
• RunOnInsecureOrigins - Allow stealth on http:// origins

Testing

Integration tests target 9 bot-detection sites:

• https://www.browserscan.net/bot-detection
• https://bot.sannysoft.com/
• https://www.intoli.com/blog/not-possible-to-block-chrome-headless/chrome-headless-test.html
• https://fingerprint.com/demo
• https://arh.antoinevastel.com/bots/areyouheadless/
• https://pixelscan.net/bot-check
• https://bot.incolumitas.com/
• https://abrahamjuliot.github.io/creepjs/
• https://deviceandbrowserinfo.com/info_device

These sites can change at any time. If a site changes, update the corresponding test assertions.

Run tests (Playwright browsers install automatically on first run):

dotnet test --solution ManagedCode.Playwright.Stealth.slnx -c Release

On Linux CI runners, set PLAYWRIGHT_INSTALL_DEPS=1 to install system dependencies (playwright install --with-deps) when tests start.

Google search verification is optional (Google may block automated traffic). Enable it with:

RUN_GOOGLE_SEARCH_TESTS=1 dotnet test --solution ManagedCode.Playwright.Stealth.slnx -c Release

Attribution

This project uses code from the original playwright_stealth repository and adapts it for .NET: https://github.com/AtuboDad/playwright_stealth

License

MIT. See LICENSE.