Privacy Policy
Last updated: October 2026
Information We Collect
dxc4.com is a chess analysis tool that operates entirely in your browser. We are committed to protecting your privacy and minimizing data collection.
Information We Do NOT Collect
- Personal identification information (name, email, address)
- Account information or user profiles
- Chess games or analysis data
- Payment or financial information
- Location data
Technical Information
The analytics services named below collect basic technical information automatically:
- Browser type and version
- Device type (desktop, mobile, tablet)
- General geographic region (country/state level)
- Pages visited and time spent on site
- Referring website information
How We Use Information
Any technical information collected is used solely to:
- Improve website performance and user experience
- Monitor for security threats and abuse
- Understand general usage patterns
- Fix technical issues and bugs
Local Data Storage
All chess analysis happens locally in your browser. The moves and variations you analyze live in the page's address (URL), not on a server: they are sent only where you send the link.
The one thing dxc4.com stores on your device is the list of puzzles you have solved, in your browser's local storage. It never leaves your device, and clearing your browser's site data removes it.
Third-Party Services
dxc4.com uses the following third-party services:
Stockfish Chess Engine
We use the open-source Stockfish 19 chess engine for position analysis. dxc4.com serves the engine itself, and all analysis is performed locally in your browser — no chess positions or moves are sent to external servers.
Chess.com
When you import games, your browser asks Chess.com's public API for the archive of the username you enter. That request goes from your browser straight to Chess.com and is covered by Chess.com's own privacy policy; dxc4.com does not see or keep the username or the games.
Web Analytics
We use two analytics services to understand how the site is used:
- Google Analytics, which sets first-party cookies and sends usage data (pages visited, device and browser type, approximate location, referring site) to Google
- Vercel Web Analytics, which counts page views without cookies
Neither receives your games, your analysis or your puzzle progress.
Cookies and Tracking
- The only cookies are Google Analytics' first-party cookies
- We do not use advertising or marketing cookies
- We do not use cross-site tracking
- You can block cookies in your browser without affecting any feature of the site
Data Security
We implement appropriate security measures to protect any information processed through our website:
- HTTPS encryption for all communications
- Regular security updates and monitoring
- Minimal data collection and retention
- No storage of sensitive personal information
Your Rights
You have the following rights regarding your data:
- Right to know what information is collected
- Right to access any information we have
- Right to correct inaccurate information
- Right to delete your information
- Right to opt-out of any optional data collection
Since we collect minimal information and most functionality is client-side, these rights are largely built into how our service works.
Changes to This Policy
We may update this privacy policy from time to time. Any changes will be posted on this page with an updated revision date.
Contact
If you have questions about this privacy policy or our data practices, contact dxc4.com's maker, Field Bureau & Werkstatt, at fieldbw.com.