Legal

Terms of use

Last updated: October 10, 2026.

Who we are

System Design Factory is sold and run by GUILHERME DE BRITO OLIVEIRA DESENVOLVIMENTO DE SISTEMAS, a Brazilian company (CNPJ 33.639.852/0001-82) based in Natal, RN, Brazil (“we”). Write to us at support@systemdesignfactory.com.

The service

System Design Factory lets you practice system design: you build Designs, run them and see which Checks they pass. Without an account, everything stays on your device. With an account, your work is also kept on our servers so you can use it on other devices.

Plans and payment

• Free: the Exercises marked free and the Sandbox.
• Pro: every Exercise. Monthly and annual plans renew automatically until you cancel; the lifetime plan is paid once.
• Payments are processed by Stripe. We never see or store your card.
• Prices are shown before you pay, and taxes may be added where the law asks for them.
• You can cancel a subscription at any time in My progress → Manage billing. You keep Pro until the end of the period you paid for.

Refunds

Your first payment can be refunded in full within 14 days. See Refunds. This never limits the rights consumer law gives you where you live.

Your account and your work

• Your Designs and notes are yours. We use them only to run the service for you.
• You can download everything we hold about you and delete your account at any time, in My progress → Your data.
• Deleting your account cancels any subscription at once, with no refund for the time left.

Fair use

Do not attack the service, try to reach other people’s data, resell access, or copy the Exercises’ content to publish it elsewhere. We may close an account that does, after telling you why.

Availability and liability

We work to keep the service available and your work safe, but we cannot promise it will never be down. To the extent the law allows, our liability is limited to what you paid us in the last 12 months.

Changes

If we change these terms in a way that matters to you, we will tell you before the change applies. A paid period already started keeps the terms it was bought under.

Law

These terms follow the laws of Brazil, including the Consumer Defense Code. If you are a consumer elsewhere, the protections of your own country’s law still apply.