FuckClaude - an open-source browser environment self-testing tool. Will it be flagged with CC (Distributed Content Violation) tags?

What is FuckClaude?

FuckClaude is a lightweight, SEO-friendly, bilingual (Chinese and English) single-page application (SPA) detection tool used to scan a user's browser environment and determine if they will be flagged as a "Chinese user" by Claude Code. After running the tool, it will perform a scan with animated GIFs, and the score ring will increase as the risk accumulates, ultimately providing a conclusion and a list of flagged signals. All detection is completed on the local browser without initiating any network requests or uploading any data.

FuckClaude's main functions

• Browser environment fingerprintingIt scans the local browser environment with one click and uses 6 signals (system time zone, browser language, installed Chinese fonts, Intl locale settings, time zone offset, and Emoji rendering style) to determine whether a user will be marked as a "Chinese user" by Claude Code.
• Real-time risk scoring and visualizationEach signal outputs a "China similarity" of 0–1, which is multiplied by the weight and accumulated, with a total score of 100 points. The three risk levels of low (0–30), medium (31–60), and high (61–100) are displayed intuitively with dynamic score rings and scanning animations.
• Local privacy protectionAll detection is 100% completed locally in the browser, without initiating any network requests or uploading any user data, thus fully protecting privacy.
• Detailed display of hit signalAfter the scan is completed, a clear conclusion is given, and all “hit” signals with a score ≥ 0.25 and their specific detection values are listed to help users accurately locate the source of risk.
• Chinese and English bilingual interfaceBuilt-in English (/) and Chinese (/zh/It supports bilingual language, automatically adapts to user language preferences, and generates SEO-friendly sitemaps and hreflang links.
• Open source and deployableBased on Astro 7.x static output, with no UI framework dependency, it can be deployed to any static hosting platform such as Cloudflare Pages, Vercel, Netlify, and GitHub Pages with one click.
• The technical principles are transparent and open.Based on publicly available reverse engineering analysis of early relay fingerprinting behavior of Claude Code, this article details detection mechanisms such as time zone steganography (date separator variants, Unicode apostrophe switching), for technical reference only.

Follow us on WeChat and reply with "open source",join inAI open source project discussion group

How to use FuckClaude

• Use directly onlineOpen your browser and visit https://fuck-claude.app/ (English) or https://fuck-claude.app/zh (Chinese). Once on the page, click the scan button to start the scan with one click.
• View scan resultsWait for the item-by-item scanning animation to complete, observe the score ring change in real time as the risk accumulates, and finally view the risk level determination (low/medium/high) and a detailed list of all hit signals.
• Local development and deploymentExecute after cloning the repository pnpm install Install dependencies and run. pnpm dev Start the local development server (default address) http://localhost:4321),pass pnpm build Building static artifacts to dist/ Table of contents, then use pnpm preview Preview the build results.
• Custom domain deploymentBefore deploying to static hosting platforms such as Cloudflare Pages, Vercel, Netlify, or GitHub Pages, astro.config.mjs In site fields and public/robots.txt Replace it with your real domain name and ensure the canonical link is correct.hreflang The sitemap is pointing to the correct location.
• Switch language versionUse the language switch button on the page to switch to English (/) and Chinese (/zh/You can freely switch between interfaces to obtain the detection results and descriptions in the corresponding language.
• Understanding the Detection PrincipleRead the explanation of the principles at the bottom of the page to understand the detection methods and weight logic of each signal, and adjust your browser environment settings (such as time zone, language, etc.) accordingly based on the items you have matched.

FuckClaude's official website address

• Official website addresshttps://fuck-claude.app/
• Github repositoryhttps://github.com/LinXiaoTao/FuckClaude

Application scenarios of FuckClaude

• Claude Code transit user environment self-checkUsing unofficial API relay nodes (via ANTHROPIC_BASE_URL Developers or teams configuring this feature should quickly check whether their local browser/system environment has high-risk characteristics that could be flagged as "Chinese users" by Claude Code before connecting.
• Browser fingerprinting technology researchSecurity researchers and reverse engineering enthusiasts can study Claude Code's early proxy fingerprinting and steganography mechanisms (time zone mapping, date separator variants, Unicode apostrophe switching, etc.) as a technical reference case for browser fingerprinting detection and anti-detection.
• Privacy Feature Self-CheckFor privacy-sensitive users, this feature allows them to understand which "Chinese environment fingerprints" (time zone, language, installed fonts, etc.) their browsers have leaked through a 100% locally run scan without exposing any data.
• Risk control bypass effect verificationOperators using anti-fingerprinting tools such as Roxy browser or multi-account isolation environments should verify whether the current environment has successfully blocked underlying fingerprints such as Canvas, WebGL, and time zones, thereby reducing the probability of being blocked by AI platform risk control.