Privacy Policy

• No ads, no third-party trackers, no advertising SDKs and no cookies. Page views are counted with Cloudflare Web Analytics, which is cookieless and doesn't identify you.
• On the web, your progress lives in your browser. With Full Access it also syncs between your browsers, stored under a SHA-256 hash of your license key. The key itself is never stored on our server.
• Lemon Squeezy sells the web license as merchant of record. We never see your card details.
• The app keeps your progress on your devices and, if you leave sync on, in your own iCloud account. We can't see it.

Who runs it

The site and the web app are served by Cloudflare, through a Cloudflare Worker (a small program that runs on Cloudflare's network). Like any web host, Cloudflare processes your IP address and request details to deliver the pages and protect the service. We don't keep our own access logs.

What stays in your browser

The web app saves your study data in your browser's local storage, on your device:

• which questions you have answered, whether you were right, when, and where each one sits in the review schedule,
• your finished mock papers and a paper in progress,
• your free-tier counters, the credential you picked and your appearance choice (light, dark or automatic),
• with Full Access, your license key and this browser's activation ID, so the next visit can unlock again.

Clearing the site's data in your browser removes all of it. Free use sends nothing about your answers to us: the free questions load from a public file.

Full Access and your license key

When you unlock, the web app sends your license key and this browser's activation ID to our Worker. The Worker checks them with Lemon Squeezy's license service and, if the key is valid, returns the question bank. A successful check is remembered for about ten minutes in the Worker's memory, so the key isn't checked on every request. The key is not written to any database.

Lemon Squeezy is the merchant of record for the web license: it takes the payment, handles sales tax and issues the license key. Its own privacy policy covers the checkout. As the seller we can see the order in Lemon Squeezy (your name, email address, country, what you bought and the license key), which we use only to answer support questions and handle refunds. We never receive card details.

Sync between your browsers

With Full Access, your progress is copied to our Worker's database (Cloudflare D1) so your browsers match. Each browser stores one record:

• the same study data as above: per question, the number of attempts and correct answers, the last result and when it was, and its review box; your finished mock papers; and the time of your last "Reset all progress",
• a label for the browser, such as "Chrome on Windows", and the activation ID Lemon Squeezy gave it.

Records are filed under a SHA-256 hash of your license key. The raw key is never stored. Not synced: your appearance choice, the chosen credential, the free-tier counters and a paper in progress.

A browser's record stays when you free its slot, so your progress comes back when you enter the key again. "Reset all progress" clears progress on every synced browser. To have the synced records for your key deleted from our database, email us from the address you bought with.

Analytics

The site uses Cloudflare Web Analytics to count page views, referring sites and page load times. It sets no cookies, doesn't use local storage, and doesn't identify or follow individual visitors. Cloudflare adds a small script to each page to do this. The web app's study data is never part of it.

The app does not collect any personal information. There is no account, no analytics, and no developer server. The only network traffic is Apple's: the App Store for the optional Full Access purchase and, if you leave iCloud sync on, your own iCloud account carrying your progress between your devices.

What the app stores, and where

The app saves your study data so your progress survives between sessions: which questions you have answered and whether you answered them correctly, the spaced-review schedule built from those answers, your mock paper scores and timings, your control-room simulator runs, and which credential you have selected. All of it is written to files inside the app's own storage on your device; on a Mac, inside the app's sandbox container. It is never sent to any server belonging to us, and we can't see it.

iCloud sync

With iCloud sync on (Library › Sync, on unless you turn it off), each of your devices also keeps a copy of its own progress in the private database of your iCloud account, through Apple's CloudKit, so your iPhone, iPad and Mac can combine their progress. Only devices signed in to your Apple Account can read that copy. We have no access to it, and it counts toward your own iCloud storage (a few tens of kilobytes per device). Turn sync off in the Library to keep progress on one device only. To delete the iCloud copy, use Settings › your name › iCloud › Storage › Grid Prep on an iPhone or iPad.

You can erase your progress at any time with "Reset all progress" in the Library tab: with sync on, on every device signed in to your iCloud account. Deleting the app deletes the copy on that device.

Network access and purchases

Every question, reference card and explanation is bundled inside the app. The one-line diagrams, contingency analysis reports, AGC control boards and calculation drills are generated on the device, and everything works offline. The optional Full Access purchase is handled entirely by Apple through the App Store: Apple processes the payment and tells the app on your device whether the purchase exists. We receive no personal or payment information. The app keeps only a count of the free questions, mock papers and simulator runs used, on your device and, with iCloud sync on, in your iCloud account, so the free allowance is shared by your devices.

Grid Prep is a study aid for grid control-room operators. It is not directed at children, and the app is rated 4+ because it collects no data from anyone.

If Grid Prep changes in a way that affects this policy, this page will be updated first, and the date at the top will change.

Questions about this policy can be sent to patrguzz@gmail.com.