About Check-san
Check-san is a free web tool that allows anyone to easily check the information being sent to websites and services when connecting to the internet.
Why We Built This
When using the internet, we unknowingly share a lot of information with the sites we visit — IP address, browser type, screen resolution, language settings, and more. All of this can be easily obtained by websites. Check-san was created to make this 'invisible information' visible and raise awareness about online privacy.
Key Features
- IP address and GeoIP location display
- Browser, device, and hardware detection
- Connection protocol details (HTTP/TLS/ALPN)
- Browser fingerprint uniqueness scoring
- Security score for connection environment
- DNS leak testing
- AI-powered privacy risk analysis
- Location-based privacy risk assessment
Our Privacy Commitment
Check-san does not store or accumulate any displayed information on the server. All data is fetched and displayed in real time, and discarded when you leave the page. The AI analysis feature only uses country and region-level data — personally identifiable information such as IP addresses is never sent to external services.
Technology Stack
Check-san is built with Node.js (Express) on the backend, using EJS templates for server-side rendering. The infrastructure runs on AWS (Lambda, CloudFront, Route 53), with MaxMind GeoLite2 for GeoIP data and Amazon Bedrock for AI analysis.