Privacy policy

All of this is stored in your browser, on your device: your progress (the lessons and problems you've completed, and when), your code drafts, the name you write on your certificate, and your dark or light mode choice. None of it reaches us, except what you send when you request a verified certificate, as explained below.

The sign-in provider sends us your email address and your account ID on their service, and may also send your name and profile picture. We save these in your account with us. We never see your password, and we don't ask for any other access to your account.

We also save your progress (the ID of each lesson you've completed and when) linked to your account, so it follows you across your devices. No one else can read this data: the database prevents each user from seeing anyone else's.

These languages are compiled on a server, so only your code is sent to the Judge0 execution service, with no information about you, and the result comes back to you. All other languages run entirely in your browser.

We re-grade your exam answers on the server. Only the answers are sent, with no information about you, to the Judge0 execution service, or to a browser run by Cloudflare for the web exam, and the results come back.

If they pass, we save the certificate record: its ID, your account ID, the two names you entered, the exam it's for, the number of problems and checks, and the date of issue. We also save your answers as they were graded, so we can refer to them if anyone questions a certificate. No one can write to this record from the browser.

Anyone with the certificate's ID or link, or who scans the QR code printed on it, can see its page. The page shows both names, the certificate type, its date and its ID, and the name appears in the link preview when you share it. It doesn't show your email, your account or your answers, and it doesn't appear in search results.

As on any website, our hosting logs technical data about requests, such as IP address and browser type, to run and protect the site. We use your IP address briefly to limit code runs when they repeat too often, and we don't keep it after that. When you request a certificate, we count your attempts by account ID and by IP address (or its first half, for IPv6) to limit repeated requests, and we delete this count after two days.

• We don't show ads, and we don't use cookies for tracking or marketing.
• We don't sell your data, or share it with anyone for their own use.

• Cloudflare hosts the site and stores the certificate records in a D1 database, and its Browser Rendering service re-grades web exam answers when you request a verified certificate.
• Supabase manages accounts and stores progress.
• Google and GitHub let you sign in with your account there.
• Judge0 runs C++‎, C#‎ and Java code, and re-grades the answers for the other exams when you request a verified certificate.

The “Start over” button on your dashboard clears your progress from both your browser and your account, and leaves your verified certificates untouched. To delete your account entirely, email us at the address below. We'll delete it along with its certificates and their answers, and those certificates' pages will then say they don't exist. To revoke a single certificate, email us as well. Its page will stay up and say it was revoked, without showing your name.