Privacy Policy

We collect personal information that you provide to us.

We collect personal information that you voluntarily provide to us when you register on the Services, express an interest in obtaining information about us or our products and Services, when you participate in activities on the Services, or otherwise when you contact us.

Personal Information Provided by You. The personal information we collect may include:

• names
• email addresses
• usernames
• passwords
• contact or authentication data

Sensitive Information. We do not process sensitive information.

Payment Data. We may collect data necessary to process your payment if you choose to make purchases. All payment data is handled and stored by Lemon Squeezy. You may find their privacy notice here: https://www.lemonsqueezy.com/privacy (opens in a new tab).

All personal information that you provide to us must be true, complete, and accurate, and you must notify us of any changes to such personal information.

In Short: We process your information to provide, improve, and administer our Services, communicate with you, for security and fraud prevention, and to comply with law.

We process your personal information for a variety of reasons, including:

• To facilitate account creation and authentication and otherwise manage user accounts.
• To deliver and facilitate delivery of services to the user.
• To respond to user inquiries/offer support to users.
• To send administrative information to you.
• To fulfill and manage your orders. We may process your information to fulfill and manage your orders, payments, returns, and exchanges.
• To enable user-to-user communications.
• To save or protect an individual’s vital interest.

In Short: We only process your personal information when we believe it is necessary and we have a valid legal reason to do so under applicable law.

If you are located in the EU or UK, this section applies to you.

The GDPR and UK GDPR require us to explain the valid legal bases we rely on. We may rely on:

• Consent. We may process your information if you have given us permission. You can withdraw your consent at any time.
• Performance of a Contract. We may process your personal information when necessary to fulfill our contractual obligations to you.
• Legal Obligations. We may process your information where necessary for compliance with our legal obligations.
• Vital Interests. We may process your information where necessary to protect your vital interests.

If you are located in Canada, this section applies to you.

We may process your information if you have given us specific permission (express consent) or where implied consent applies. You can withdraw your consent at any time.

In Short: We may share information in specific situations described in this section and/or with the following third parties.

We may need to share your personal information in the following situations:

• Business Transfers. We may share or transfer your information in connection with any merger, sale of company assets, financing, or acquisition of all or a portion of our business.
• Other Users. When you share personal information or otherwise interact with public areas of the Services, such personal information may be viewed by all users.
• Advertising and Measurement Partners. When we advertise Stydra, we share limited measurement data with Meta Platforms (Facebook and Instagram) so that we can tell which adverts brought people here.

What the advertising measurement covers. A Meta measurement tool (the “Meta pixel”) loads in your browser on every page of the site, so that it is already there if you move onto a page we do measure; it is silent everywhere else. It reports that a page was viewed only from a fixed list of pages — the homepage, our marketing and comparison pages, the free demo, sign-up, the page where a demo pack is claimed, and the first-run setup that follows sign-up — and our servers may send Meta a matching report of the same moment. What is reported is that a page was viewed, that a demo pack was produced, that an account was created, or that someone continued to our checkout. Those reports carry the address of the page you were on, your IP address and browser user agent, Meta cookies (_fbp and _fbc) if your browser holds them, a one-way SHA-256 hash of the random identifier in the stydra_anon cookie described under Cookies and similar technologies, and — when you are signed in — a one-way SHA-256 hash of your email address together with your account identifier. The hashed stydra_anon identifier is what lets Meta recognise the anonymous demo, the sign-up and the purchase that come out of one browser as one person rather than three. A hash is not reversible into your address, and it is sent so that Meta can match an advert to a result without us handing over the address itself. When you buy a plan, the report of that purchase also carries a SHA-256 hash of the name you gave at checkout and the browser user agent from the page you started the checkout on, and it may carry the Meta click identifier from the advert you first arrived through, which we keep on your account from sign-up. Our servers also re-issue the two Meta cookies with a longer expiry when your browser sends them to us; where the pixel never ran, they write a _fbp of their own, and rebuild _fbc from the click identifier in the advert link you arrived on. That is so a purchase made days after an advert can still be matched to it.

These reports never contain your notes, your uploads, your study packs, your flashcards, your quiz answers, or anything you say to the tutor, and they are never sent from a page whose address identifies one of your packs: those pages are excluded from this reporting by design, and we redact any identifier out of an address before it is stored or shared. Meta processes what it receives as an independent controller under its own terms; you can read those, and change what Meta does with it, in your Meta account settings. Where we advertise is limited, and where advertising is switched off no such tool loads and nothing is sent. None of it runs at all for a visitor in the EEA or the UK who has not said yes, and anyone can switch it off at any time — see Your privacy choices and Cookies and similar technologies.

In Short: We offer products, features, or tools powered by artificial intelligence, machine learning, or similar technologies. What you send them is used to produce your result and is not used to train them.

As part of our Services, we offer products, features, or tools powered by artificial intelligence, machine learning, or similar technologies (collectively, “AI Products”). The terms in this Privacy Notice govern your use of the AI Products within our Services.

Use of AI Technologies

We provide the AI Products through a third-party service provider (“AI Service Provider”): Anthropic. Your input, output, and personal information will be shared with and processed by this AI Service Provider. You must not use the AI Products in any way that violates its terms or policies.

Your material is not used to train AI models. Under the commercial terms we are on with our AI Service Provider, what you send — your notes, your uploads, your questions — is used to produce your result and is not used to train its models. We do not train models of our own on your material, and we do not sell it. This is a statement about the arrangement we are on today: if we change AI Service Provider, or the terms we are on with one, this section is where that change is written down.

Our spoken-audio features — the podcast recap, the tutor’s spoken replies, and the voice tutor — run entirely in your own browser using its built-in speech engine. Nothing you hear or say in those features is sent to us or to any third party.

Our AI Products

Our AI Products are designed for AI-powered study assistance including flashcard generation, quiz creation, problem solving, tutoring, and audio recap features.

How We Process Your Data Using AI

All personal information processed using our AI Products is handled in line with our Privacy Notice and our agreements with third parties. This ensures high security and safeguards your personal information throughout the process.

In Short: We may transfer, store, and process your information in countries other than your own.

Our servers are located in the United States. Regardless of your location, please be aware that your information may be transferred to, stored by, and processed by us in the United States and other countries.

If you are a resident in the EEA, UK, or Switzerland, these countries may not have data protection laws as comprehensive as those in your country. However, we will take all necessary measures to protect your personal information in accordance with this Privacy Notice and applicable law.

We have implemented measures including the European Commission’s Standard Contractual Clauses for transfers of personal information. Our Standard Contractual Clauses can be provided upon request.

In Short: We keep your information for as long as necessary to fulfill the purposes outlined in this Privacy Notice unless otherwise required by law.

We will only keep your personal information for as long as it is necessary for the purposes set out in this Privacy Notice. As a rule that period is the time in which you have an account with us: close the account and the packs, study progress, exam dates, deep dives, settings and profile that name you are deleted with it.

Two things are deliberately kept beyond the life of an account, and neither of them names you. The first is the record that a browser has already used its one free demo. It is kept indefinitely, because the point of it is that the free demo cannot be reset by closing an account and opening another; it holds a one-way salted hash of an IP address, the time it was written, and — where that demo was later claimed by an account — that account’s identifier, which identifies nobody once the account is gone. The second is the measurement rows described in Section 4 that were written before anyone signed in: they record that a page was viewed or that a demo pack was produced, and they name a random visitor identifier rather than a person. We do not delete those on a fixed schedule today, with one exception inside them. If you reached us from an advertisement, the click identifier that advertisement attached to your visit is erased thirty days after it was written — from those rows and from any account record carrying it — because once the advertising network’s attribution window has closed that identifier can attribute nothing, and all it can still do is let another company match the visit back to you. The rows themselves stay, and so do our own labels for which campaign a visit came from; what goes is the identifier that is not ours. The measurement rows written after you sign in do name your account, and those are deleted with it.

When we have no ongoing legitimate business need to process your personal information, we will either delete or anonymize such information, or securely store it and isolate it from any further processing until deletion is possible.

In Short: We aim to protect your personal information through a system of organizational and technical security measures.

We have implemented appropriate and reasonable technical and organizational security measures designed to protect the security of any personal information we process. However, despite our safeguards and efforts to secure your information, no electronic transmission over the Internet or information storage technology can be guaranteed to be 100% secure. You should only access the Services within a secure environment.

In Short: We do not knowingly collect data from or market to children under 14 years of age.

We do not knowingly collect personal information from children under 14. Users aged 14-17 must have a parent or guardian’s permission, as stated in our Terms of Service. If you believe a child under 14 has given us personal information, contact us at brandonyoo3147@gmail.com and we will delete it.

In Short: Depending on your state of residence in the US or in some regions, such as the EEA, UK, Switzerland, and Canada, you have rights that allow you greater access to and control over your personal information.

In some regions (like the EEA, UK, Switzerland, and Canada), you have certain rights under applicable data protection laws. These may include the right (i) to request access and obtain a copy of your personal information, (ii) to request rectification or erasure; (iii) to restrict the processing of your personal information; (iv) if applicable, to data portability; and (v) not to be subject to automated decision-making. In certain circumstances, you may also have the right to object to the processing of your personal information.

We will consider and act upon any request in accordance with applicable data protection laws.

If you are located in the EEA or UK and you believe we are unlawfully processing your personal information, you also have the right to complain to your Member State data protection authority (opens in a new tab) or UK data protection authority (opens in a new tab).

However, please note that this will not affect the lawfulness of the processing before its withdrawal.

Account information

If you would at any time like to review or change the information in your account or terminate your account, you can log in to your account settings and update your user account.

Closing your account does not cancel a paid subscription. Cancel the subscription first — Manage billing in your account settings opens Lemon Squeezy’s cancellation page for it — or email us at brandonyoo3147@gmail.com and we will cancel it for you. Closing the account removes the stored link to that page, and a subscription still running afterwards keeps billing until it is cancelled.

Upon your request to terminate your account, we will deactivate or delete your account and information from our active databases. However, we may retain some information in our files to prevent fraud, troubleshoot problems, assist with any investigations, enforce our legal terms and/or comply with applicable legal requirements.

If you have questions or comments about your privacy rights, you may email us at brandonyoo3147@gmail.com.

We honour Global Privacy Control (GPC) signals: when your browser sends one, we do not load the Meta pixel or send events to Meta. The single exception is a choice you made here yourself — if you have pressed Allow under Your privacy choices, that answer is more specific than a browser-wide default and it stands until you change it back.

The older Do-Not-Track (“DNT”) header is a different signal, and no uniform standard for it was ever finalised. California law requires us to tell you how we treat it: we do not act on DNT itself. GPC is the signal we honour, and the switch in the next section does the same job in a browser that sends neither.

In Short: A handful, and each one has a job you can point at. None of the advertising ones exist unless measurement is allowed.

• _fbp and _fbc — Meta’s own cookies. _fbp is normally written in your browser by the Meta pixel, and where the pixel could not run our servers write one instead; _fbc is written by the pixel from the click identifier in an advert link, and our servers rebuild it from that same identifier when the cookie is missing. Both are re-issued by our servers with a longer expiry, as described in Section 4. They are what lets Meta match a purchase back to the advert that was clicked. They are only ever set where measurement is allowed: never for a visitor in the EEA or the UK who has not said yes, and never for anyone who has opted out or whose browser sends GPC.
• stydra_try — set when you run the free demo. It holds a random identifier, signed so that it cannot be edited into somebody else’s, and it is the whole of how we give one demo pack per browser without asking you to sign up first. Your browser will not let any page script read it. It is not advertising, and it is set whatever you have answered about measurement.
• stydra_anon — a random identifier that lets us count one visit as one visit rather than a string of unrelated page views. A one-way SHA-256 hash of it is also sent to Meta with the reports described in Section 4, which is how a demo run before you had an account and a sign-up or purchase from the same browser later are recognised as one person. It is written only where measurement is allowed, and it is deliberately a different identifier from the one above, so that the demo cap and the analytics cannot be joined up.
• stydra_region — written at our edge from the country your IP address resolves to, and holding nothing but a marker meaning “consent has to be asked here”. It is what makes the consent question appear in the EEA and the UK.
• stydra_consent — your answer to that question, so that we do not ask twice and so that every page can check it before measuring anything. A copy is kept in your browser’s local storage as well, because Safari expires a cookie written this way after seven days.

Two more things live in your browser’s local storage rather than in a cookie. stydra-theme remembers whether you chose the light or the dark theme and is never sent anywhere. Your Supabase session token is what keeps you signed in between visits, and it goes back to our servers only to prove that a request is yours. Clearing this site’s data in your browser removes all of the above, and signs you out.

In Short: If you are a resident of California, Colorado, Connecticut, Delaware, Florida, Indiana, Iowa, Kentucky, Maryland, Minnesota, Montana, Nebraska, New Hampshire, New Jersey, Oregon, Rhode Island, Tennessee, Texas, Utah, or Virginia, you may have the right to request access to and receive details about the personal information we maintain about you and how we have processed it, correct inaccuracies, get a copy of, or delete your personal information.

Categories of personal information we collect

We will use and retain the collected personal information as needed to provide the Services or for as long as the user has an account with us.

Your rights

You have rights under certain US state data protection laws, including:

• Right to know whether or not we are processing your personal data
• Right to access your personal data
• Right to correct inaccuracies in your personal data
• Right to request the deletion of your personal data
• Right to obtain a copy of the personal data you previously shared with us
• Right to non-discrimination for exercising your rights
• Right to opt out of the processing of your personal data if it is used for targeted advertising, the sale of personal data, or profiling

How to exercise your rights

To exercise these rights, you can email us at brandonyoo3147@gmail.com, download a copy of your data or delete your account in your account settings (login required at stydra.xyz/auth (opens in a new tab)), or refer to the contact details at the bottom of this document.

Request verification

Upon receiving your request, we will need to verify your identity to determine you are the same person about whom we have the information in our system.

Appeals

Under certain US state data protection laws, if we decline to take action regarding your request, you may appeal our decision by emailing us at brandonyoo3147@gmail.com. If your appeal is denied, you may submit a complaint to your state attorney general.

California “Shine The Light” law

California Civil Code Section 1798.83, also known as the “Shine The Light” law, permits our users who are California residents to request and obtain from us, once a year and free of charge, information about categories of personal information (if any) we disclosed to third parties for direct marketing purposes. If you are a California resident and would like to make such a request, please submit your request in writing to us using the contact details provided in section How can you contact us about this notice?

In Short: You may have additional rights based on the country you reside in.

Australia

We collect and process your personal information under the obligations and conditions set by Australia’s Privacy Act 1988 (Privacy Act).

This Privacy Notice satisfies the notice requirements defined in the Privacy Act, in particular: what personal information we collect from you, from which sources, for which purposes, and other recipients of your personal information.

If you believe we are unlawfully processing your personal information, you have the right to submit a complaint about a breach of the Australian Privacy Principles to the Office of the Australian Information Commissioner (opens in a new tab).

In Short: Yes, we will update this notice as necessary to stay compliant with relevant laws.

We may update this Privacy Notice from time to time. The updated version will be indicated by an updated “Revised” date at the top of this Privacy Notice. If we make material changes to this Privacy Notice, we may notify you either by prominently posting a notice of such changes or by directly sending you a notification. We encourage you to review this Privacy Notice frequently to be informed of how we are protecting your information.

The controller of the personal information described in this notice is the individual who operates Stydra, based in Seoul, Republic of Korea. Stydra is a service run by one person rather than a company, and there is no data protection officer or representative to name.

If you have questions or comments about this notice, you may email us at brandonyoo3147@gmail.com.

Based on the applicable laws of your country or state of residence in the US, you may have the right to request access to the personal information we collect from you, details about how we have processed it, correct inaccuracies, or delete your personal information. You may also have the right to withdraw your consent to our processing of your personal information. To request to review, update, or delete your personal information, please visit: https://stydra.xyz/settings (opens in a new tab).