Chrome X-Browser-Validation Header Reverse Engineering & Generator
Chrome recently added a few new headers:
"x-browser-channel": "stable", "x-browser-copyright": "Copyright 2025 Google LLC. All rights reserved.", "x-browser-validation": "6h3XF8YcD8syi2FF2BbuE2KllQo=", "x-browser-year": "2025"
Apart from one of them, there isn’t much that’s interesting. They’re just bits of client specific information. However, base64 decoding x-browser-validation yields what appears to be a hash whose purpose remains undocumented.
Chrome almost certainly uses this header as an integrity signal. Verifying that the declared user agent matches the underlying platform, spotting user agent string spoofing attempts etc.
Generator
from xbv import generate_validation_header ua = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36" # You may supply an explicit api_key alongside the ua # if omitted, the function automatically selects the appropriate key based on the user agent api_key = "AIzaSyA2KlwBX3mkFo30om9LUFYQhpqLoa_BNhE" header_value = generate_validation_header ( ua ) print ( header_value )
How the Header Is Made
Grab two strings A hard-coded, platform specific API key
The browser’s full user agent string Concatenate DATA = API_KEY + USER_AGENT Hash DATA with SHA-1 and base64 encode it.
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