What this site records

When you open the home page, a blog post, a study note, /resources, /about or a project page, the server (a Cloudflare Worker) stores one row in a database on Cloudflare:

• the time, the page path and the page you came from (referrer);
• your IP address, and the country, region, city, time zone and network operator that Cloudflare derives from it;
• your browser's user-agent string and preferred languages;
• technical details of the connection: Cloudflare data centre, HTTP and TLS version, round-trip time, and whether Cloudflare verified the visitor as a known crawler.

Cloudflare also offers latitude, longitude and postal code for each request; they are not stored. The /syllabus pages are served as plain files and are not logged.

A small script on the same pages (written for this site, no third-party library) reports back once the page has loaded, after 15 seconds and when you leave:

• a random ID kept in your browser's local storage under _pk, so repeat visits from the same browser count once;
• whether you scrolled, clicked, typed or moved the pointer, how long the page stayed open and how far you scrolled;
• screen size, device time zone, number of CPU cores, approximate memory, touch support, and the connection type, bandwidth and latency the browser estimates.

It does not read your graphics card, device model or anything else used to fingerprint a browser.

Page-view rows are deleted automatically once they are older than 90 days. A short per-IP summary (last visit and whether it looked like a bot) is deleted after 90 days without a visit. Nothing is sold or shared; the data stays in my Cloudflare account, which hosts the site.

• The syllabus remembers your light/dark choice and the last lesson you read in each course (local storage).
• A service worker keeps pages you have opened so they work offline.

Neither is sent anywhere. Clearing this site's data in your browser removes them, and the _pk ID with them.

• Home page: Open-Meteo (weather in Da Nang), the npm registry and download API (package versions and downloads), and the GitHub API (public repository count).
• Project pages: the npm registry and download API.
• Contact form: what you type is sent to Web3Forms, which forwards it to my email.

Like any web request, these services see your IP address. They are not given anything else by this site.

With JavaScript turned off, only the server row is recorded. To have the records tied to your IP address or browser ID deleted, email phamkhanhminhman97@gmail.com.