Privacy Policy

What Demist does

Demist transcribes your lectures, reads them back, and explains and translates unfamiliar terminology in real time, building a personal glossary for you to review — built for students who find lectures harder to follow. This policy explains what data we collect, why, and how it is handled.

Data we collect

• Email address: used only for authentication via a one-time code. We do not send marketing emails.
• Audio recordings: microphone audio is captured in short chunks, sent to Groq or OpenAI for transcription, and immediately discarded. We do not store audio files. If you turn on Private transcription in settings, microphone audio is transcribed entirely on your device and is never sent to us or any provider.
• Transcripts: for live microphone sessions we save a transcript only if you've declared a support need in your profile, or your lecturer has consented for your module. For recordings you upload or capture from an officially provided source, transcripts are saved to your account.
• Term definitions: to define a term we send the flagged term and a short excerpt of surrounding context to OpenAI. From the web app this is a single sentence per term, never full transcripts. Nothing sent for definitions is stored by us. If you've set a translation language and downloaded the on-device model, the definition is translated on your device. If you haven't downloaded it, the same OpenAI request that generates the definition also translates it.
• Detected terms: the terms and definitions picked up from your sessions are stored in your account so you can review them later.
• Profile information: course, year of study, and date of birth. Used to tailor term explanations to your level and to keep the service age-appropriate. Date of birth is never shared.
• Support need: an optional, self-declared category (hearing, reading/dyslexia, focus/attention, language, or unspecified) used only to unlock full transcript saving without requiring lecturer consent each time. You choose whether to set this, can change it any time in your profile, and it is never shared or used for any other purpose.
• Session data: timestamps and duration of recording sessions. Used to calculate your streak and weekly stats.
• Flashcard history: your grading responses (Again / Hard / Good / Easy) used to schedule spaced repetition reviews.
• Usage analytics: anonymised events (e.g. "recording started", "flashcard graded") collected via PostHog to help us improve the product. No personal data is included in these events.
• Pro waitlist: if you join the waitlist we store your email and which feature prompted you, used only to contact you about Pro.

Third-party services

• Supabase: database and authentication. Your data is stored in Supabase's EU infrastructure.
• Groq & OpenAI: audio is transcribed using Groq's and/or OpenAI's APIs, and term detection uses OpenAI. If you haven't downloaded the on-device translation model, definition translation also uses OpenAI. Audio is processed in real time and not stored by us. These providers are based in the United States; data is transferred under their data processing agreements and standard contractual clauses, and is not used to train their models.
• PostHog: product analytics. Events are anonymised before being sent.

Data sharing

We do not sell, rent, or share your personal data with any third party outside of the services listed above.

Data retention and deletion

Your data is kept for as long as your account is active. You can delete your account and all associated data at any time by emailing us at the address below. We'll process deletion requests within 30 days.

Cookies

We use a single session cookie to keep you logged in. No advertising or tracking cookies.

Contact

Questions about this policy or your data: privacy@demist.app

Complaints

If you have a concern about how we handle your data, email privacy@demist.app. We'll acknowledge your complaint within 30 days. You also have the right to complain to the UK Information Commissioner's Office (ico.org.uk).