THE FINE PRINT

PRIVACY

2MB Problems is a free site run by one person, Karan Mannan. This page lists everything the site keeps about you, who can see it, which other services are involved, and how to delete your account.

In short: the server keeps your sign-in email, your display name, your code and your results. It counts how the site is used under a code number instead of your name, and nothing about that is stored on your device. You can delete your account yourself with the DELETE ACCOUNT button on the HISTORY page. Your results then stay on the leaderboards under an anonymous name.

WHAT IT STORES

• Your account. When registration is open, anyone with a verified Google or GitHub address can sign in. When it is closed, only addresses the owner has allowed can sign in. When you do, the server keeps the verified email address the provider gave it, which provider you used and that provider's id number for your account (so the next sign-in finds you). It also keeps a display name based on your Google first name or your GitHub login, unless the owner picked another one when letting you in. It never sees or stores a password. Your avatar is a small pixel picture the site makes for you; it does not copy your Google or GitHub picture.
• Your sign-in session. A record that you are signed in. It ends if you stay away for 15 to 30 days, and after 90 days at most.
• Language requests. If you request a language, the server keeps its name, your account number and when you asked. The owner can see how many players requested each language. Deleting your account removes your requests.
• Your work. The code you run and submit, the language, the custom input you give a RUN, and the time. Runs from the RUN button, with their code, input and results, are removed by a cleanup that runs regularly once they are more than 7 days old. Submissions are kept, because the leaderboards are built from them.
• Your results. For every run and submission: the verdict, the memory and CPU time it used, the score, compiler messages, and the output of the sample tests. For hidden tests it keeps the verdict, the time and memory each test used and a short category such as "input not fully read", but never the test's input or what your program printed.
• The suggestion form. The idea you write and the email, if you give one, in "Suggest a problem!" on the home page. They are emailed to the owner, who reads them to pick new problems. If you ask, the owner deletes them from the mailbox by hand.
• A sign-in block. Kept only after you delete your account, or after the owner removes your address. It is a keyed fingerprint of that address in the database, not the address itself. It stops the address from making a new account on its own, and the owner can check a guessed address against it. It stays until the owner allows the address again.
• Server logs. A line for each request, with your account number but not your email. If a sign-in is refused, the log keeps the email address that tried. If a network address sends too many requests, the log keeps that address. Logs are kept for up to 30 days.
• Backups. Copies of the database, kept for up to 90 days, so nothing is lost if the server breaks.
• A deletion record. Kept only after you delete your account. It is a private file on the server with your old account number, when the account was made, the anonymous name your results now carry, when you deleted it, the code number your usage events used, and a keyed fingerprint of each email address the account had. A fingerprint cannot be turned back into an address, but the owner can check a guessed address against it. The file exists so that restoring a backup cannot bring a deleted account back. Records are dropped after 100 days, and a copy of the file goes to the backup storage with each backup.

WHAT STAYS ON YOUR DEVICE

Drafts of your code and custom input, the language you last picked for each problem, your editor font, key bindings, layout and the CRT effects switch are kept in your browser's local storage. Saving them never sends them anywhere, and they stay after you sign out. Your code and custom input reach the server only when you press RUN or SUBMIT. To remove them, clear this site's data in your browser. Deleting your account clears that account's drafts, custom input, last language and workspace layout from the browser you deleted it in. Your editor font, key bindings and CRT switch stay, and other browsers keep everything until you clear it.

WHO CAN SEE IT

• Other players see your display name, your pixel avatar and your results on the leaderboards. They never see your email address, your code or your custom input. After you delete your account they see the name "deleted-" followed by your old account number, a new avatar and the same results. People who saw the leaderboard before can still recognise those rows, because the scores and times are the same.
• The owner can see everything listed above, including your email and your code, to run the site and fix problems.

USAGE ANALYTICS

The site counts how it is used, so the owner can see where people get stuck. The server records:

• which page was opened, by a fixed name such as "problem" or "board", plus the problem's short name on a problem's pages;
• when you sign in, with Google or GitHub, and whether it was your first time;
• when you run or submit code, with the problem and the language;
• the result category you were shown, such as "accepted" or "wrong answer".

Page views are always anonymous. They carry no code number and no link to your account, whether you are signed in or not, so they are only counted. The other three kinds of event carry a code number instead of your name. The server makes it from your account number and a secret key that only the server has, so the analytics service cannot tell who you are. The owner can work it out, which is how your events can be found and deleted.

Analytics never get your code, your custom input, your email address, your display name, your network address, your browser's details, the names or contents of tests, or exit codes. They set no cookie and store nothing on your device. The page sends its name to this site's own server and nowhere else; the server passes the events on.

If your browser sends "Do Not Track" or "Global Privacy Control", page views from it are not recorded. If you object to being counted, tell the owner. Page views cannot be traced to you, so there is nothing of yours to take out of them. For your sign-in, run, submit and result events, there is no switch yet that leaves out only your account, so the owner will stop sending your events or turn analytics off for everyone. The events are kept for up to 12 months.

COOKIES

One cookie keeps you signed in. A short-lived cookie (10 minutes) carries a sign-in while it is in progress, and another, just as short, lets the "not accepted" page explain a refused sign-in; that one can hold the email address that tried. The site cannot sign you in without them, and none of them is used for analytics, advertising or tracking.

WHO ELSE IS INVOLVED

• Google and GitHub handle the sign-in. They know you signed in to this site, as they do for any site.
• Cloudflare carries the traffic between you and the server, so it sees the requests that pass through it, including your network address.
• Cloudflare storage holds the database backups (up to 90 days) and the latest copy of the deletion record.
• Web3Forms receives what you type in the suggestion form and emails it to the owner. Your browser sends the form straight to it, so it also sees your network address. Nothing else on the site talks to it.
• Mixpanel, an analytics service, receives the usage events described above, from the server only. Its servers for this site are in the European Union, and it keeps the events for up to 12 months.

Your data is not sold or used for advertising, and it goes to no one beyond the services above. It is used only to run the site and improve it.

DELETING YOUR DATA

You can delete your account yourself. Open HISTORY, find the ACCOUNT box at the bottom and press DELETE ACCOUNT. A box lists what goes and what stays, and you type DELETE to confirm. It cannot be undone. If a run or submission of yours is still queued or running, wait until it finishes.

Deleting your account does this:

• your email address, display name and sign-in accounts are removed, and your sign-in sessions end on every device. Your avatar is replaced. Your address is blocked from making a new account by itself: it can sign in again only if the owner allows it again, and then it is a new account with nothing from the old one;
• your code, custom input, compiler messages and the output and feedback of every test are removed, sample tests included;
• your results stay on the leaderboards under an anonymous name such as "deleted-7", frozen: they are not measured again when the judge changes. What stays is the verdict, the score, the memory and CPU time of each test, when you submitted, the language and the problem;
• a private deletion record is kept for 100 days, as described under WHAT IT STORES;
• your usage events at Mixpanel are not removed by the button. Ask the owner, who sends Mixpanel a request to delete the events under your code number;
• backups keep a copy for up to 90 days, and logs for up to 30, before they expire.

YOUR CHOICES

To see or correct what the site holds about you, to object to being counted, to leave the site, or to ask the owner to delete your account for you, write to the owner through the links at the bottom of this page. Deleting your account has a button. The other requests are still handled by hand. If you need something removed, ask before you submit it.

LAST UPDATED 2026-10-31 · IF THE SITE CHANGES, THIS PAGE CHANGES.