Privacy policy

Anonymous by default

You can open the board, import FEN, import PGN, make moves, review a game, and practise training positions without creating an account. No name, email address, phone number, or location is required for any of that.

What stays in your browser

The chessboard, move logic, FEN and PGN parsing, position state, and the local library all run in your browser. Your board preferences (theme, board colours, analysis depth, which side you played) are stored in your browser's local storage under keys such as aback_color_theme and aback_prefs. Nothing in local storage is transmitted to Aback servers unless you explicitly save a game to your account.

Engine analysis runs locally

Stockfish runs as WebAssembly inside a Web Worker in your browser, using your device's CPU. The positions you analyze are processed locally and are never sent to a server. This is why Aback Chess has no analysis backend and why analysis works without an account.

Accounts and synced games

If you create an account, we store your email address, an optional display name, and a one-way hash of your password. The password itself never leaves your device: it is stretched in your browser before it is sent, and only the result is stored.

When you save a game to your account, the game PGN, the starting position, the player names, and the result are stored in our database so they can be reached from another device. Review summaries and training positions are stored on the device where the review happened, unless you sign in and choose to sync them.

Every read and write of your data is checked against your session on the server. One account cannot read or change another account's games, reviews, training positions, or subscription.

Deep reviews, puzzles and email

A Deep review runs on your device like every other analysis. To apply the daily allowance, the server records which game (a short key, not the moves) you started a Deep review for on each day; earlier days are deleted as you start new ones.

If you sign in, your puzzle rating and the puzzles you have tried are stored with your account so they follow you between devices. Without an account they stay in your browser.

We email you about your account and nothing else: a welcome and a link to confirm your address when you sign up, password reset links you ask for, a notice when your password changes, changes to your Pro plan, and the result of a Deep review you chose to be told about. Apart from the account emails, we write only to an address you have confirmed. Email is sent through Cloudflare Email Sending; we keep a record of what kind of email was sent and whether it went out, not its contents.

Your profile and feedback

When you create an account we ask a few optional questions: how you would describe your chess, a rough rating, what you want to improve, and your Chess.com or Lichess username. The answers are stored with your account and used only to set where your puzzles start, to suggest what to try first, and to fill in the game import. Your usernames are used to fetch your public games when you ask, never in the background.

When you link a Chess.com or Lichess account, we fetch that account's public profile (name, ratings and game counts) and keep a copy for a few hours so pages load quickly. Lichess sometimes refuses requests from our server; your browser then asks Lichess for the same public profile directly, so Lichess sees that request come from your browser.

If you send feedback, we store your message, the page you sent it from, and, if you leave the box ticked, your browser and screen size. Signed in, it is linked to your account; without an account, any email address you add is kept only so we can reply. Feedback from an account is deleted with the account.

Payments

Payments are handled by Dodo Payments, our payment provider. Card details are entered on the provider's hosted checkout and never reach Aback servers. We store only the identifiers needed to manage your subscription, such as the customer and subscription references and the status of your plan.

Sponsor cards

The cards under the top bar are paid for by sponsors. They are images and text served from our own server: no sponsor script runs on Aback Chess, and no sponsor learns who you are from seeing a card.

To show sponsors how their card is doing, we count how many times each card was on screen for a second and how many times it was clicked, per card and per day. Those counts are all we keep: no account, address or device is stored with them. A click goes through our server, which counts it and sends you on to the sponsor's site, so the sponsor sees you arrive from abackchess.com like any other link.

If you sponsor Aback Chess, we store your card (name, line, link and logo), its review history and its numbers with your account, and the public stats page for your card shows those numbers to anyone.

Analytics

Aback Chess does not send FEN strings, PGN content, engine variations, player names, or game comments to analytics. If product-level analytics are enabled, they track events only (such as analysis started or a game reviewed) and never chess content.

Data retention and deletion

Games saved to your account can be deleted individually at any time, and deleting the last one removes the associated analysis and training positions. Locally stored games and training positions can be removed from the app or by clearing your browser's site data. You can close your account from the account page, which removes your account, games, reviews, training positions, and subscription record.

Contact

Questions about this policy can be sent through the Aback Chess contact channel on the Aback Chess website.