Privacy Notice

This Privacy Notice for Euler Studios ("we", "us", or "our") describes how and why we might access, collect, store, use, and/or share ("process") your personal information when you use our services ("Services"), including when you visit our website at https://euler.so, download and use the Euler desktop application, or otherwise engage with us in related ways, including in any sales, marketing, or events.

Questions or concerns? Reading this Privacy Notice will help you understand your privacy rights and choices. We are responsible for making decisions about how your personal information is processed. If you do not agree with our policies and practices, please do not use our Services. If you still have any questions or concerns, please contact us at support@euler.so. This Privacy Notice is part of our Terms of Service.

Summary of Key Points

This summary provides key points from our Privacy Notice, but you can find out more details about any of these topics below.

• What personal information do we process? When you visit, use, or navigate our Services, we may process personal information depending on how you interact with us and the Services, the choices you make, and the products and features you use.
• Do we process any sensitive personal information? We do not process sensitive personal information such as racial or ethnic origins, sexual orientation, or religious beliefs.
• Do we collect any information from third parties? We do not collect any information from third parties.
• How do we process your information? 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 may also process your information for other purposes with your consent.
• In what situations and with which parties do we share personal information? We may share information in specific situations and with specific third-party service providers listed in section 3 below.
• What are your rights? Depending on where you are located geographically, the applicable privacy law may mean you have certain rights regarding your personal information.
• How do you exercise your rights? The easiest way to exercise your rights is by contacting us at support@euler.so. We will consider and act upon any request in accordance with applicable data protection laws.

Table of Contents

• 1. What information do we collect?
• 2. How do we process your information?
• 3. When and with whom do we share your personal information?
• 4. Do we use cookies and other tracking technologies?
• 5. Is your information transferred internationally?
• 6. How long do we keep your information?
• 7. Do we collect information from minors?
• 8. What are your privacy rights?
• 9. Controls for Do-Not-Track features
• 10. Do we make updates to this notice?
• 11. How can you contact us about this notice?
• 12. How can you review, update, or delete the data we collect from you?

1. What information do we collect?

Personal information you disclose to us

In short. We collect personal information that you voluntarily 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. The personal information we collect may include the following, depending on how you interact with us:

• Waitlist email. If you submit your email through any of the forms on euler.so, we store that email address along with the date and the form you submitted it through.
• Account information. When account creation is available, we will store your email address, a hashed password (or your federated identity if you choose single sign-on), and the subscription tier associated with your account.
• Payment information. Subscription payments are processed by Stripe. Stripe receives your card details directly. Euler does not see or store your card number, CVC, or expiration date. We store the Stripe customer ID and subscription metadata so we can provision your tier and issue refunds when appropriate.
• Support correspondence. If you email us, we keep the email so we can reply and follow up.

Sensitive information. We do not process sensitive information.

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.

Information automatically collected

In short. Some information, such as your Internet Protocol (IP) address and/or browser and device characteristics, is collected automatically when you visit our Services.

We automatically collect certain information when you visit, use, or navigate the Services. This information does not reveal your specific identity (like your name or contact information) but may include device and usage information, such as your IP address, browser and device characteristics, operating system, language preferences, referring URLs, device name, country, location, and information about how and when you use our Services. This information is primarily needed to maintain the security and operation of our Services, and for our internal analytics, reporting, and product-improvement purposes.

Information we automatically collect includes:

• Website analytics. The marketing site uses PostHog to capture anonymous pageviews, scroll depth, click events, traffic source, browser and OS, and a randomly generated device identifier. We do not link this identifier to your name or email unless you explicitly identify yourself by signing in.
• Cloud AI request metadata. When you use the cloud AI features inside the editor, the relevant snippet of your document plus your prompt are sent to our backend, which forwards them to our model provider. We log request metadata (timestamp, account ID, token counts, model used) for abuse prevention, billing reconciliation, and product improvement.
• Crash and diagnostic reports. The desktop app may include opt-in crash reporting. If you opt in, we receive a stack trace, the OS version, the app version, and anonymous device characteristics. No document content is included.

2. How do we process your 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 may also process your information for other purposes with your consent.

We process your personal information for a variety of reasons, depending on how you interact with our Services, including:

• To deliver and facilitate delivery of Services to you.
• To respond to user inquiries and offer support to users.
• To send administrative and transactional information to you, such as purchase receipts, license keys, password resets, and product updates.
• To fulfill and manage your orders, payments, returns, and exchanges made through the Services.
• To enable user-to-user communications (for example, when real-time collaboration ships).
• To save or protect an individual's vital interest, such as preventing harm.
• To request feedback and to analyze user behavior and product usage so we can improve the Services, understand which features matter, and fix bugs.
• To send you marketing and promotional communications, if this is in accordance with your marketing preferences. You can opt out of our marketing emails at any time.
• To protect our Services, including by monitoring and preventing fraud.
• To identify usage trends.
• To determine the effectiveness of our marketing and promotional campaigns.
• To comply with our legal obligations.

3. When and with whom do we share your personal information?

In short. We may share information in specific situations described in this section and with the following third parties.

Euler does not sell your personal information. We share data with third-party service providers that help us operate the Services, and only to the extent needed for them to perform the services we have contracted them for:

• Cloudflare. Website hosting, CDN, DDoS protection, and runtime for the cloud backend.
• Supabase. Authentication and operational database.
• Stripe. Payment processing and subscription billing.
• Resend. Transactional and product emails.
• PostHog. Website and product analytics.
• Anthropic and OpenRouter. Model providers for the cloud AI features, when you use them. Cloud AI requests are processed under the model provider's terms of service.

We may also share personal information in the following situations:

• Business transfers. We may share or transfer your information in connection with, or during negotiations of, any merger, sale of company assets, financing, or acquisition of all or a portion of our business to another company.
• Legal obligations. We may disclose your information where we are legally required to do so in order to comply with applicable law, governmental requests, a judicial proceeding, court order, or legal process, such as in response to a court order or a subpoena.
• Vital interests and legal rights. We may disclose your information where we believe it is necessary to investigate, prevent, or take action regarding potential violations of our policies, suspected fraud, situations involving potential threats to the safety of any person and illegal activities, or as evidence in litigation in which we are involved.

4. Do we use cookies and other tracking technologies?

In short. We use a small number of analytics cookies, and only after you accept them.

The marketing site at euler.so uses PostHog for product analytics. PostHog sets a first-party cookie and a matching entry in your browser's local storage. These are used to count unique visits, measure which pages and links people interact with, and track conversions on the waitlist forms. We do not run advertising trackers, we do not share this data with ad networks, and we do not sell it.

Routing. Analytics requests are sent to a path on our own domain (euler.so/api/u/) and then forwarded to PostHog by our Cloudflare Worker. PostHog is still the processor; only the network path changes. We do this so common ad-blocker lists don't drop requests on the way out and so browser cookies from the euler.so origin aren't forwarded upstream.

Consent. If you visit from the EU, EEA, UK, or Switzerland, we show a banner on your first visit asking whether you want to accept analytics cookies, and until you accept PostHog is loaded in a no-op state and does not send any events or set identifying cookies. If you visit from a jurisdiction where prior consent is not required (for example the United States), we treat the visit as consented on arrival so we can measure pageviews, but you can revoke that at any time using the controls below and we will stop capturing. Either way, we remember your choice in a small local storage entry named euler_cookie_consent, and if your browser sends a Do-Not-Track signal we treat it as a rejection automatically regardless of your location.

Managing your choice. You can change your mind at any time using the controls below.

5. Is your information transferred internationally?

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

Our servers are located in the United States and the European Union. Regardless of your location, please be aware that your information may be transferred to, stored by, and processed by us in our facilities and in the facilities of the third parties with whom we may share your personal information (see section 3 above).

If you are a resident in the European Economic Area (EEA), United Kingdom (UK), or Switzerland, then these countries may not necessarily have data protection laws or other similar 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.

6. How long do we keep your information?

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, unless a longer retention period is required or permitted by law (such as tax, accounting, or other legal requirements).

When we have no ongoing legitimate business need to process your personal information, we will either delete or anonymize such information, or, if this is not possible (for example, because your personal information has been stored in backup archives), then we will securely store your personal information and isolate it from any further processing until deletion is possible.

7. Do we collect information from minors?

In short. We do not knowingly collect data from or market to children under 18 years of age.

We do not knowingly collect, solicit data from, or market to children under 18 years of age, nor do we knowingly sell such personal information. By using the Services, you represent that you are at least 18 or that you are the parent or guardian of such a minor and consent to such minor dependent's use of the Services. If we learn that personal information from users less than 18 years of age has been collected, we will deactivate the account and take reasonable measures to promptly delete such data from our records. If you become aware of any data we may have collected from children under age 18, please contact us at support@euler.so.

8. What are your privacy rights?

In short. You may review, change, or terminate your account at any time, depending on your country, province, or state of residence.

Withdrawing your consent. If we are relying on your consent to process your personal information, which may be express and/or implied consent depending on the applicable law, you have the right to withdraw your consent at any time. You can withdraw your consent at any time by contacting us at support@euler.so. However, please note that this will not affect the lawfulness of the processing before its withdrawal nor, when applicable law allows, will it affect the processing of your personal information conducted in reliance on lawful processing grounds other than consent.

Opting out of marketing communications. You can unsubscribe from our marketing and promotional communications at any time by clicking on the unsubscribe link in the emails that we send, or by contacting us. You will then be removed from the marketing lists. However, we may still communicate with you, for example to send you service-related messages that are necessary for the administration and use of your account, to respond to service requests, or for other non-marketing purposes.

Account information. If you would at any time like to review or change the information in your account or terminate your account, you can contact us at support@euler.so. 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.

9. Controls for Do-Not-Track features

Most web browsers and some mobile operating systems and mobile applications include a Do-Not-Track ("DNT") feature or setting you can activate to signal your privacy preference not to have data about your online browsing activities monitored and collected. The euler.so marketing site honors DNT: if your browser sends a DNT signal, PostHog analytics are disabled automatically and the consent banner treats you as having rejected analytics cookies, without you having to click anything.

10. Do we make updates to this notice?

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 "Last updated" 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.

11. How can you contact us about this notice?

If you have questions or comments about this notice, you may email us at support@euler.so.

12. How can you review, update, or delete the data we collect from you?

Based on the applicable laws of your country, 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. These rights may be limited in some circumstances by applicable law. To request to review, update, or delete your personal information, please email support@euler.so.