$ cat ~/privacy.md

Privacy & analytics.

This is a personal site and a free system-design course. I measure how it is used so I can make the lessons better. No ads, no selling or sharing data with advertisers, and you can switch analytics off below.

Stored in this browser only. Global Privacy Control is honoured automatically. Do Not Track is not: it is a retired browser setting with no agreed meaning, so use the switch above instead.

01 · what is recorded

Visits and learning activity

Page views and reading time: the page, referrer and campaign tags, device type, browser, screen size, approximate country/city (from the request, the IP address itself is not stored), time actively reading and how far you scrolled.
Learning events: lessons opened and completed, sections read, quiz and trial answers, searches (length only, never the text), shares, "Ask AI" clicks, games played.
Offline reading: what you save for offline reading (which article or world, and its size), opening saved copies and installing the app. Events from while you're offline, like stages cleared, wait on your device and are sent when you're back online.
If you sign in: your email, name and avatar from the sign-in provider, plus your progress, streaks, notes, bookmarks and comments, so they follow you across devices.
Profile photo: if you upload one, it's cropped to a small square on your device (location and camera details are removed), stored, and shown publicly next to your comments and on your profile. Remove it any time from the avatar picker; the file is deleted.

02 · tools

Which analytics tools run

First-party analytics (always): sent to this site's own API and stored in its database (Supabase).
PostHog (active): product analytics, heatmaps and session replay. Requests go through this site's own domain. Signed-in visitors are linked to their account ID and email so I can follow a learner's journey and help when something breaks.
Google Analytics 4 (active): aggregate traffic reports. Advertising features, ad personalisation and ad storage are switched off (Consent Mode: ad_storage denied).

03 · session replay

What a session recording shows

A replay is a reconstruction of the page (not a video of your screen): clicks, scrolling and page changes. Everything you type is masked: email and code fields, notes, comment drafts and every other input appear as asterisks. Pages under /admin are never recorded. Recordings are kept for about a month, then deleted by PostHog.

04 · your choices

Opting out and deleting data

Use the switch at the top of this page (or "opt out" in the footer). It stops all three analytics tools in this browser.
Turn on Global Privacy Control in your browser (built into Brave and Firefox, or an extension elsewhere): the site then sends nothing to PostHog or Google. The older Do Not Track setting doesn't switch analytics off; use the switch above.
Reset your learning progress any time from your progress page.
To delete your account and its data, or to ask what is stored about you, email kukreja.him@gmail.com.

last updated · October 2026

Visits and learning activity

Page views and reading time: the page, referrer and campaign tags, device type, browser, screen size, approximate country/city (from the request, the IP address itself is not stored), time actively reading and how far you scrolled.
Learning events: lessons opened and completed, sections read, quiz and trial answers, searches (length only, never the text), shares, "Ask AI" clicks, games played.
Offline reading: what you save for offline reading (which article or world, and its size), opening saved copies and installing the app. Events from while you're offline, like stages cleared, wait on your device and are sent when you're back online.
If you sign in: your email, name and avatar from the sign-in provider, plus your progress, streaks, notes, bookmarks and comments, so they follow you across devices.
Profile photo: if you upload one, it's cropped to a small square on your device (location and camera details are removed), stored, and shown publicly next to your comments and on your profile. Remove it any time from the avatar picker; the file is deleted.

Which analytics tools run

First-party analytics (always): sent to this site's own API and stored in its database (Supabase).
PostHog (active): product analytics, heatmaps and session replay. Requests go through this site's own domain. Signed-in visitors are linked to their account ID and email so I can follow a learner's journey and help when something breaks.
Google Analytics 4 (active): aggregate traffic reports. Advertising features, ad personalisation and ad storage are switched off (Consent Mode: ad_storage denied).

What a session recording shows

Opting out and deleting data

Use the switch at the top of this page (or "opt out" in the footer). It stops all three analytics tools in this browser.
Turn on Global Privacy Control in your browser (built into Brave and Firefox, or an extension elsewhere): the site then sends nothing to PostHog or Google. The older Do Not Track setting doesn't switch analytics off; use the switch above.
Reset your learning progress any time from your progress page.
To delete your account and its data, or to ask what is stored about you, email kukreja.him@gmail.com.