Privacy policy

What this site stores, what leaves your device, and what you can do about it. Last updated 22 October 2026.

The short version

You can use the entire course without an account, and if you do, your progress never leaves your browser. If you choose to create an account, your progress is synced to a database so you can pick it up on another device. Page-view and performance analytics are collected for everyone. Advertising may appear and, when it does, is served by Google.

Nothing here is sold, and nothing is shared with anyone beyond the specific services named below.

What is stored on your device

KashSec progress normally uses one browser-storage entry, kashsec_state_v1. It holds your lesson progress, quiz and exam results, practice-task answers, flashcard scheduling, notes you have written, lessons you have rated, your streak, study-plan settings, starting-route preferences, investigation decisions and analyst notes, playground completion, and display settings. Playground messages and experiment settings are not saved or synced. If this record becomes unreadable, KashSec tries to keep an untouched second local entry, kashsec_state_recovery_v1, so you can download the original data. Clearing this site's storage deletes both entries.

This is stored by your browser, on your device. Without an account it is never transmitted anywhere, and it is not readable by this site's author or anyone else. Clearing browser storage for this site erases both entries permanently — export a copy first if you need one.

If you create an account (optional)

Accounts are optional and exist for one reason: using the site on more than one device. Sign-in is by a one-time link sent to your email address, or through Google. Authentication and storage are handled by Supabase, a third-party database service.

With an account, the following is stored on Supabase's servers: your email address, held for authentication; the progress record described above; your lesson ratings, if you rate any lessons; and — only if you separately opt in to the public leaderboard — a display name of your choosing and a count of lessons completed. The leaderboard is off unless you turn it on, and turning it off removes your row.

You can export everything from the progress page at any time, and deleting your account deletes the stored record.

Analytics

Two Vercel services run on every visit: Web Analytics, which counts page views, and Speed Insights, which measures how fast pages load. Both are used in aggregate to see which lessons people read and which pages are slow. They are not used to build a profile of you and are not tied to an account.

To be exact about the mechanism: these load from a third-party CDN and therefore see your IP address and browser as part of any ordinary web request.

Advertising

This site participates in Google AdSense. When ads are being served, Google and its partners may use cookies or similar identifiers to select and measure them, including based on your prior visits to this and other sites.

You can control this directly at Google's My Ad Center, and opt out of personalised advertising there or at aboutads.info. In the EU and UK, a consent prompt is shown before any personalised advertising cookie is set.

What this site does not do

There is no tracking pixel, no session recording, no heatmap tool, no fingerprinting script, and no advertising network other than the one named above. Your notes, your answers and your search queries are never transmitted to the author. Nothing is sold or licensed to a data broker.

The security tools on this site process everything in your browser. Text you paste into an encoder, a hash identifier or a header analyser is not uploaded anywhere.

Children

This site is not directed at children under 13 and no account should be created by one. Nothing here is knowingly collected from a child.

Your choices

You can use the site without an account; your learning progress then stays in your browser, while page analytics and any advertising still operate as described above. Delete local progress by clearing site storage in your browser settings. Export or delete an account and its data from the progress page. Opt out of personalised advertising with the links above. The lessons and tools work if third-party analytics are blocked.

Changes and contact

If what the site collects changes, this page changes in the same update, and the date at the top moves. Questions about any of it go through the contact page.