Terms of Service

System Design Atlas (“the atlas”, “the site”) is a reading site for system design interviews: concept modules, technology pages, worked designs with architecture diagrams, a course and a coding track. It is run by Mert Kahyaoğlu, a sole trader in the United Kingdom trading as System Design Atlas (“we”, “us”). Our address and email are at the end of these terms.

Every page without a lock is free to read, with or without an account. We revise pages as we learn, and we may move, merge or retire one.

Pages and features marked with a lock are premium. Lifetime Access unlocks all of them, including premium pages and features published after you buy. It is one payment, not a subscription: nothing renews and nothing is charged again.

The price is shown on the Premium page in US dollars and includes any VAT or sales tax, so it is what you pay. Checkout shows the total again before you pay, and if it converts the price into your currency, the converted amount is the one charged. You must be 18 or over to buy Lifetime Access.

While the price is marked “early access”, it is lower than the price we plan to charge once more premium pages are published. Buying at it gets you the same Lifetime Access as buying later, including everything added afterwards.

“Lifetime” means for as long as we run System Design Atlas, not for your lifetime or ours. If the atlas ever closes, Lifetime Access ends with it, and we will announce the closure on the site before it happens. Premium pages are revised like every other page, and a premium page may occasionally be retired.

Lifetime Access belongs to the account you bought it with and can’t be moved to another account or person. It ends if the payment is fully refunded, and it is paused while a dispute or chargeback on the payment is open: it comes back if the dispute is decided in our favour and ends if it isn’t. The Refund Policy explains refunds.

Checkout is run by Stripe, and we never see your card details. For most purchases Stripe acts as the merchant of record through Stripe Managed Payments: Stripe sells you Lifetime Access on our behalf, takes the payment, charges and pays any VAT or sales tax, sends the receipt, and deals with payment questions and disputes, under Stripe’s own terms shown at checkout. Where Managed Payments doesn’t apply to a purchase, we sell it to you directly.

Either way, we supply the premium pages and features, and these terms are the agreement for using them. Ask us about anything to do with the content or your access.

If you are a consumer in the UK or the EU, the law normally gives you 14 days to cancel a contract made online. Premium pages are digital content that opens as soon as your payment clears, so before checkout we ask you to request access straight away and to confirm you understand that you lose that right to cancel once access starts. You can’t buy without doing so.

After that, the Refund Policy applies: generally there are no refunds for a change of mind, but your rights below if something is wrong with what you bought always apply.

The premium pages and features have to match their description on the site, be of satisfactory quality and be fit for purpose. If they aren’t, tell us: we will fix the problem, and if we can’t do that within a reasonable time or without significant inconvenience to you, you can have some or all of your money back.

If anything we supply damages your device or other digital content because we didn’t use reasonable care and skill, we will repair the damage or compensate you for it.

Accounts are run by Clerk, which handles sign-in for us. You need an account to buy Lifetime Access and to read premium pages. You must be at least 16 to create one.

One account is for one person. Keep your sign-in to yourself; you are responsible for what happens under your account. If you think someone else has used it, tell us at tulparapps@gmail.com.

You can stop using the atlas whenever you like, and ask us to delete your account at the address above. Lifetime Access is recorded on your account, so deleting the account ends Lifetime Access too.

When you use the atlas, don’t:

• scrape it, download it in bulk, or feed premium pages to tools that copy them out of the site;
• copy, publish, share or sell premium pages, in whole or in large part, anywhere outside the atlas;
• share your account, or let more than one person use it;
• get around the lock on premium pages, or help anyone else do so;
• attack, overload or interfere with the site or the services it runs on.

Quoting a short passage with a credit and a link, the way you would quote a book, is fine. If an account breaks these rules, we may suspend or close it. An account closed for breaking these rules is not refunded, unless the law says it must be.

The writing, diagrams and visualisations on the atlas are copyright of Mert Kahyaoğlu. The name System Design Atlas and the site’s design are ours too. Buying Lifetime Access gives you a personal right to read premium pages on the atlas; it doesn’t transfer any ownership.

The free documents are published under the Creative Commons Attribution-ShareAlike 4.0 licence. You may share, translate and build on them, as long as you credit “System Design Atlas by Mert Kahyaoğlu” with a link back and license what you build from them the same way. The application code is published under the MIT License.

Premium pages are not covered by either licence. All rights in them are reserved, and the only right you get to them is the one above: to read them on the atlas while you have Lifetime Access.

The atlas is educational material. We work to get the numbers, behaviours and trade-offs right, but pages can contain mistakes or go out of date, and real systems differ. Check anything you rely on for production work.

We can’t promise any outcome from using it: not a passed interview, not an offer, not a level. Designs named after real products are our own reconstructions for study. They are not affiliated with or endorsed by those companies, and may not match how their systems actually work.

The site is provided as it is and as available. We try to keep it running and correct, but we don’t promise it will always be available, uninterrupted or free of errors.

As far as the law allows, we are not liable for indirect or consequential losses from using the atlas, such as lost opportunities, lost earnings or lost data. Our total liability to you for anything to do with the atlas is limited to what you paid us in the twelve months before the claim.

Nothing in these terms limits liability that the law doesn’t allow to be limited, such as for fraud, or for death or personal injury caused by negligence, and nothing takes away rights you have as a consumer.

We may update these terms as the atlas changes. The date at the top of the page changes with them, and we will say so on the site when a change matters to people who have bought Lifetime Access. If you keep using the atlas after a change, the new terms apply. Changing the terms doesn’t, by itself, take away Lifetime Access you have already paid for.

These terms are governed by the law of England and Wales, and its courts hear any dispute about them. If you are a consumer, you also keep the protection of the law where you live, and can bring a claim in your local courts.

System Design Atlas is a trading name of Mert Kahyaoğlu, a sole trader in the United Kingdom. Write to tulparapps@gmail.com about anything on this page.

Post: 195 Ballards Lane, London N3 1LP, United Kingdom