Terms of Service

Effective date: 2026-10-12 · Version: 2026-10-v2

These terms are an agreement between you and Dennis Kaydalov, an individual / sole trader based in Toronto, Canada who runs Sketchy Systems ("we", "us"). They cover your use of the Sketchy Systems simulator at [sketchysystems.dev]/app/, including the tutorial and challenges (the "Service"). Contact: support@sketchysystems.dev.

The short version: you pay US$14.99 a month plus applicable tax after a 7-day free trial, and you can cancel online at any time. Payments aren't refundable except where the law requires it.

1. Accounts

• You need an account to use the Service. You sign in with your email address. We send you a sign-in link, and there is no password.
• You must be at least 16. To start a subscription you must be an adult (18, or the age of majority where you live), or have a parent or guardian do it for you.
• Keep access to your email account secure, because anyone who can read your email can sign in as you. Accounts are for one person. Don't share your account.

2. Subscription, free trial and payment

• Price: US$14.99 per month, plus any sales tax, VAT or GST that applies where you live, calculated at checkout. Your exact total, in your local currency where available, is shown at checkout.
• Free trial: new subscribers get a 7-day free trial, once per person. You need a valid payment card to start it. We won't charge you during the trial.
• Automatic renewal: if you don't cancel before your trial ends, you're charged US$14.99 plus applicable tax when the trial ends, and again every month on the same date, until you cancel. Before you start, we show you the exact date of your first charge. About 4 days before the trial ends, we email you a reminder.
• If we find that someone has already had a trial (for example under another email address), we may end the extra trial early. We will never charge you because we ended a trial.
• Who takes your payment: you pay on Stripe's secure checkout, and your subscription is sold through Link, Stripe's merchant of record service. Link is the seller of the subscription and handles billing, tax, receipts and invoices, and its Sold Through Link Terms also apply to your purchase. You can also manage or cancel your subscription at link.com. Our cancellation terms here and our Refund Policy are in addition to Link's terms.
• Failed payments: if a renewal payment fails, Stripe will retry it and Link will email you. If it still fails, your access may be paused until the payment goes through. If the first payment after your free trial fails, the simulator stays locked until you subscribe again with a working card.
• Price changes: if we ever change the price, we'll email you between 7 and 30 days before it applies to you, and tell you how to cancel. You can cancel before the new price applies, and you won't be charged it.

3. Cancelling

• You can cancel at any time, online: in the simulator go to Menu → Manage subscription, or use the Cancel subscription link at the bottom of every page. You can also email us.
• Cancelling stops all future charges. You keep access until the end of your trial or the month you've already paid for. After that, the simulator is locked until you subscribe again.
• If you cancel during the trial, you won't be charged at all.

4. Refunds

Payments aren't refundable, including for partial months or unused time, except where the law requires it or these terms say so. We may refund a payment at our discretion. A full refund cancels the subscription straight away and ends access. If you live in the EU, UK or another country that gives you a legal right to cancel or withdraw, you keep that right: Link, as the seller, handles those requests. See the Refund Policy for the details.

5. Your diagrams

• Your diagrams, settings and progress are saved by your browser on the device you use, not stored on our servers, so we can't recover them. If you clear your browser's site data, they're deleted, so export a copy (Menu → Download as .json).
• Your diagrams are yours. We claim no rights in them.
• You can export your diagrams even when you don't have an active subscription, at /export/.

6. Using the Service

While your trial or subscription is active, we give you a personal, non-transferable licence to use the Service for learning, practice, teaching and your own work. Please don't:

• share your account or resell access;
• copy, scrape or redistribute the Service, its challenges or its content in bulk;
• try to get around the paywall, attack, overload or probe the Service, or reverse-engineer it, except as far as the law allows you to;
• use it to break the law.

We may suspend or close an account that seriously or repeatedly breaks these rules. If we close your account and you've done nothing wrong, we'll refund the unused part of your current month.

7. The simulator is a teaching tool

The Service is a simplified simulation. Its numbers are illustrative. It is not an engineering, capacity-planning or professional tool, so don't rely on it for real production decisions.

8. Changes and availability

• We keep improving the Service and may add, change or remove features. If a change significantly reduces what you're paying for, we'll tell you in advance, and you can cancel and get a refund of the unused part of your month.
• We try to keep the Service available, but we can't promise it will always be available or error-free.
• If we change these terms in a way that matters, we'll email you at least 14 days before the changes take effect. If you don't agree, you can cancel before then. Small changes, such as typo fixes or new contact details, apply when we post them.

9. Our liability

• We provide the Service "as is", as far as the law allows.
• As far as the law allows, we are not liable for indirect or unforeseeable losses, or for lost diagrams or other data we don't store (see section 5). Our total liability to you is capped at the amount you paid us in the 12 months before the claim.
• None of this limits liability that cannot legally be limited (for example for death or personal injury caused by negligence, fraud, or your statutory consumer rights). If you're a consumer in the EU or UK, you keep all the rights your local law gives you.

10. Governing law

These terms are governed by the laws of Ontario, Canada. If you're a consumer, you keep the protection of the mandatory laws of the country where you live, and you can bring a claim in your local courts. Please contact us first. Most problems can be fixed with an email.

11. Contact

Dennis Kaydalov, trading as Sketchy Systems · support@sketchysystems.dev