Privacy notice

Updated 4 November 2026

Cube3D (立方体数理), at cube3d.app, provides interactive learning experiments. This notice explains the information used to operate the current service.

Free experiments and family accounts

Three selected experiments can be explored without registration. Account management, purchases and invitation applications are intended for parents, guardians and teachers. Please do not submit a student's name, school or date of birth. Optional age or school-stage preferences are saved in your browser; a selected stage may also appear in a filter URL.

Sign-in information

Email sign-in uses a verification link or code sent through Resend. Google sign-in requests only basic identity and verified email (openid and email); it does not access Gmail or Google Drive. We check Google's account identifier and verified email to complete sign-in, and retain the email for your Cube3D account. We use account records, verification challenges, hashed session tokens and invitation bindings to authenticate users and enforce access limits. Signing in alone does not unlock paid experiments.

Payments and access

Stripe hosts checkout and processes payment details. Cube3D stores order and checkout identifiers, the plan, payment status and verified buyer email, plus the email-backup choice. Cube3D does not receive or store your full card number. A paid pass is associated with the buyer's email; an optional sharing code can bind additional verified emails within the displayed three-email limit. If requested, Resend sends a sharing-code backup to the verified buyer email.

Applications and messages

Mainland China invitation applications may include a WeChat ID, phone number or email so we can review and respond. Teacher waiting-list and custom-production requests may include email, topic, school stage and teaching goals. Submit only contact information you are authorized to share. Applications do not automatically grant access.

Service providers and security

Our hosting infrastructure uses Sites and Cloudflare. Google, Stripe and Resend process information needed for their respective sign-in, payment and email functions. Infrastructure may process IP address, browser information and approximate country to serve requests, apply regional access rules and prevent abuse. Cube3D's rate-limit records use hashes rather than raw IP addresses. Session cookies keep you signed in; a language cookie remembers your selection. Google account data is used for sign-in and account access, not advertising.

Website analytics

We use Cloudflare Web Analytics to understand page views, visits and page performance, with breakdowns such as page path, referring site, country, browser and device type. Sign-in and purchase entry pages and protected teaching materials are excluded from our analytics script. We do not send account emails, invitation codes or form contents as analytics events. See Cloudflare Web Analytics documentation for details.

Retention and your choices

We retain information needed to administer accounts, access periods, orders, applications and service security. You can sign out, clear browser preferences and remove Cube3D's Google access in your Google Account. Removing Google access does not itself delete Cube3D records. To request access, correction or deletion of your information, email guoqishao@gmail.com. We may need to verify ownership and retain information required for orders, dispute handling or legal obligations.

Contact and updates

Questions about Cube3D privacy: guoqishao@gmail.com. Changes to this notice will appear here with an updated date.