Privacy Policy

1. Who we are

Do App Dev (“Etuder”, “we”, “us”) is the controller of personal data for your account and for use of the Etuder website, daily etudes, archive, billing and related services (the “Service”).

If you put other people’s personal data in submitted code, you are the controller of that data and we are the processor - see the Data Processing Addendum.

Privacy contact: mail@etuder.dev.

2. What we process

• Account: name, email, password hash, preferred coding language, interface language, reminder preference, encrypted Slack and Discord webhook URLs, reminder schedule and time zone, and when you accepted the Terms.
• Practice: submitted code, language, verdict, runtime, and the calendar day an attempt is for (including catch-up days on Pro).
• Billing: plan, Stripe customer and subscription identifiers, and payment status. Card numbers are handled by Stripe, not stored by us.
• Optional analytics: pseudonymous identifiers, named screens and interface elements, task identifiers and outcomes, payment events, traffic sources, page visit duration, and numeric page performance measurements (LCP, INP, CLS and FCP). Page paths use route templates without personal parameters. We use PostHog’s EU service with your consent to understand and improve the Service. Names, email addresses, code, passwords, form contents, full URLs and query strings, error messages, IP addresses, user agents and session recordings are excluded from analytics. Analytics events are retained for up to one year; withdrawing consent stops new collection and pending delivery. Previously collected data can be deleted on request.
• Technical logs: IP address, user agent, and similar data needed to run and secure the Service.

Do not put secrets or other people’s private data in code you submit. That is also forbidden by the Acceptable Use Policy.

3. Why, and on what legal basis

We process this data to create and secure your account, serve today’s etude, run tests in a sandbox, keep your streak and catch-up history, send optional daily reminders by email or to your chosen Slack or Discord channel, take payment, prevent abuse, and meet legal duties.

Legal bases: performance of the contract (the Terms), legitimate interests (security, keeping the product working), consent where a reminder or optional cookie is involved, and legal obligation (tax, accounting, requests we must answer).

An account is required to run or submit an etude. You can use the landing page without an account.

4. Reminders

Daily reminders are available on every plan and require you to opt in. We email you or post to your connected Slack or Discord channel when today’s etude is still unsolved. Slack and Discord messages are visible to people with access to that channel and follow the subscribing account’s progress. We store your Slack and Discord webhook URLs encrypted. Turn reminders off in Settings. Pausing reminders keeps the connection. Disconnecting a channel removes its stored connection. Existing email preferences require confirmation in Settings before reminders resume.

5. Processors and transfers

We use processors to host the Service, run submitted code in a sandbox, send email, deliver reminders through Slack or Discord when connected, and bill Pro. We do not sell personal data.

• Stripe, Inc. and its affiliates - Payment processing, invoicing, tax collection, and the customer billing portal (United States and EEA)
• Hosting and infrastructure providers engaged to run the Service - Application hosting, databases, backups, email delivery, and related operations (As disclosed by the operator on request)

Stripe’s own notice is at stripe.com/privacy. Some processors are outside the EEA or UK. Where that happens we rely on a lawful transfer tool (for example Standard Contractual Clauses) or a processor’s listed safeguards.

Customer Personal Data inside code is covered by the DPA.

6. Cookies

We use essential cookies: session, CSRF protection, and an interface-language cookie if you pick a language. Theme preference stays in your browser, not in a cookie. With your consent, Etuder stores encrypted analytics preference, random pseudonym and first-attribution cookies. The browser sends events only to Etuder; our server forwards allowed events to PostHog. You can withdraw consent through “Analytics preferences” at the bottom of any page. Details are in the Cookie Policy.

7. How long we keep data

Account, submissions and reminder preference stay while the account exists. Billing records stay as long as tax and accounting law require. Security logs are kept only as long as needed to run and protect the Service. Stripe keeps payment data under its own policy.

8. Your rights

Depending on where you live (including the EEA and UK) you may ask to access, correct, delete, or export your data, to object or restrict processing, and to withdraw consent for reminders. Email mail@etuder.dev. You may also complain to your data protection authority.

We do not use your data for automated decisions that produce legal or similarly significant effects. A streak is a practice counter, not a credit score or a hiring result.

9. Children

The Service is for people 18 or older. We do not knowingly collect personal data from children.

10. Changes

We may update this policy. The effective date is at the top of the page. Material changes will be posted here. Continued use after the date means you have read the new text.