Fingerprint Consistency

Anti-bot systems detect crawlers not by individual fingerprint values, but by inconsistencies between them. A UA claiming Chrome on Windows but WebGL reporting an Apple GPU is an instant flag. Feedstock's enhanced stealth generates profiles where all 17+ attributes agree. Based on FP-Inconsistent.

The Problem

Basic stealth overrides a few values independently:

// Old approach: 3 naive overrides, many inconsistencies
navigator.webdriver = false;
navigator.plugins = [1, 2, 3, 4, 5]; // obviously fake
navigator.languages = ['en-US', 'en'];
// But: UA says Chrome 120, WebGL says Apple M1, platform says Linux... 🚩

Enhanced Stealth

import { applyEnhancedStealth } from "feedstock";

// Auto-generates a random consistent profile
crawler.setHook("onPageCreated", async (page) => {
  await applyEnhancedStealth(page);
});

Or with a specific platform:

import { generateProfile, applyFingerprintProfile } from "feedstock";

const profile = generateProfile("chrome-mac");

crawler.setHook("onPageCreated", async (page) => {
  await applyFingerprintProfile(page, profile);
});

Profile Presets

chrome-windows

• Platform: Win32
• UA: Windows NT 10.0; Win64; x64
• WebGL: NVIDIA, AMD, or Intel (DirectX-based ANGLE)
• Screen: 1920x1080, 2560x1440, 1366x768
• Touch: 0 (desktop)

chrome-mac

• Platform: MacIntel
• UA: Macintosh; Intel Mac OS X 10_15_7
• WebGL: Apple M1/M2 or Intel Iris
• Screen: 1440x900, 2560x1600 (Retina, pixelRatio=2)
• Touch: 0 (desktop)

chrome-linux

• Platform: Linux x86_64
• UA: X11; Linux x86_64
• WebGL: NVIDIA or AMD (no Apple)
• Screen: 1920x1080, 2560x1440

What Gets Overridden

All 17+ attributes are set in a single page.evaluate() call for spatial consistency:

Consistency Guarantees

The key insight: every attribute is derived from the same base profile, not randomly generated independently.

• Windows profile → DirectX ANGLE renderer, Win32 platform, Windows UA
• Mac profile → Apple/Intel GPU, MacIntel platform, Macintosh UA
• Canvas noise uses a fixed seed per profile → same fingerprint across repeated checks (temporal consistency)

Config

const crawler = new WebCrawler({
  config: {
    stealth: true,
    fingerprintPreset: "chrome-mac",  // or "chrome-windows", "chrome-linux"
  },
});

When fingerprintPreset is set, the enhanced stealth profile is used instead of the basic stealth overrides.

Generating Profiles

import { generateProfile, generateRandomProfile } from "feedstock";

// Specific preset
const macProfile = generateProfile("chrome-mac");
console.log(macProfile.userAgent);    // "Mozilla/5.0 (Macintosh; ..."
console.log(macProfile.webglVendor);  // "Google Inc. (Apple)"
console.log(macProfile.platform);     // "MacIntel"

// Random consistent profile
const random = generateRandomProfile();