Privacy Policy

What We Collect

• Account data: your email address, which we use for sign-in links and account email, and your plan and subscription status.
• Your content: the structures and documents you save, the AI chat messages saved with each document, and images you upload for structure recognition.
• Your AI API key, if you add one (see AI Features).
• Payment data, if you subscribe (see Payments).
• Usage and device data: pages you visit, features you use, session recordings of the app (see Analytics, Session Recording and Cookies), your browser and device type, your IP address, and the approximate location derived from it.
• Error reports: when the app hits an error, a report with the error, the request it was handling, your IP address and your browser.
• Feedback you send us from the app, with your account email so we can reply.

How We Use Your Data

• To provide the ChemStitch service: saving your work, running chemistry calculations and answering your AI requests
• To send you sign-in links, trial and billing notices, and important service updates
• To bill your subscription
• To understand how the product is used and to fix problems, using the analytics and error reports described below
• To measure which of our ads bring visitors and sign-ups

We do not sell your data.

AI Features

When you use AI chat, we send your message and the structure context that goes with it (for example, the SMILES of the structure on your canvas) to OpenAI or Anthropic, through our AI gateway, to generate the answer. When you upload an image for structure recognition, we send the image to OpenAI. Nothing is sent to an AI provider unless you use one of these features. Your chat history is saved with its document in your account.

If you add your own OpenAI or Anthropic API key, we encrypt it with AES-256-GCM before storing it. We use it only to send your AI requests to that provider, and those requests are also covered by your own agreement with the provider. You can delete your key at any time in Settings.

Analytics, Session Recording and Cookies

We use PostHog for product analytics on the app and this website. It records the pages you view and the buttons and links you use. In the app, it also makes session recordings of your screen activity, with everything you type into form fields masked. When you are signed in, these events are linked to your account ID and your email domain (for example, “university.edu”, not your full address), so this data is pseudonymous, not anonymous. If your browser sends a Do Not Track signal, we do not load PostHog.

We use Google Analytics and the Reddit advertising pixel on the app and this website to measure traffic and to see which ads lead to visits and sign-ups. Both set cookies and receive your IP address and browser details. This website also loads its fonts from Google Fonts, which receives your IP address. You can block these cookies and scripts in your browser settings or with a content blocker, and ChemStitch keeps working without them.

Payments

Subscriptions are handled by Stripe. When you subscribe or manage your subscription, you enter your name, billing address and card details on Stripe’s checkout and customer portal pages. Stripe holds your card details; we never see or store them. Stripe sends us your subscription status, plan and billing period so we can give you the right access.

Who Receives Your Data

We share personal data only with the service providers below, which process it on our behalf to run ChemStitch. Our Subprocessors page lists what data each one receives and where it is located.

• Supabase: Database, authentication and file storage
• Vercel: Hosting for the app and this website, server-side API routes, runtime logs
• Railway: Hosting for the chemistry API (property calculation, naming) and the AI gateway
• OpenAI: AI chat and structure recognition from images (when you use them)
• Anthropic: AI chat (when you use it)
• Stripe: Payments, subscriptions and invoices
• Resend: Transactional email (trial, billing and account notices)
• PostHog: Product analytics on the app and this website
• Google Analytics: Website and app traffic analytics, sign-up conversion measurement
• Google Fonts: Serving the typefaces on this website (the app hosts its own fonts)
• Reddit (advertising pixel): Measuring visits from our Reddit ads
• Sentry: Error monitoring for the app
• GitHub: Tracking the in-app feedback you send us

We may also disclose data when the law requires it, for example to respond to a valid court order.

Data Storage

Your account data and content are stored in a managed database in the United States, with encryption at rest. All connections use TLS encryption in transit. Our service providers are also located in the United States.

Retention, Export and Deletion

We keep your account data and content while your account is open. Deleting a document also deletes its chat history.

You can download all your documents and chat history at any time in Settings → Account data.

To delete your account and all associated data, email support@chemstitch.ai. Stripe keeps its records of past payments as the law requires.

Your Choices

You can ask us for a copy of your data, to correct it, or to delete it, by emailing support@chemstitch.ai. You can block analytics and advertising cookies in your browser, as described above.

Changes to This Policy

When we change this policy, we update the date at the top of this page.

Contact

For privacy questions, contact support@chemstitch.ai.