Privacy Policy

What we keep

• Your email address, so we can send you sign-in codes. If you sign in with Google or Apple, we get your email and name from them. If you set a password, it’s kept only in scrambled form.
• What you put in Lucida: your decks, cards, pictures and sounds, your reviews and grades, and your settings.
• What a deck keeps about where its cards came from: its Guide (the page you write under a deck) and its Sources, which are the files, recordings, videos, pasted text and topics you made cards from, with the file or recording itself if you kept it. Sources are private to you, even on a shared deck; a shared deck’s page may say how many it has, and shows its Guide.
• Your personal AI link, the private address your AI apps use to reach your cards, and the AI apps you allowed to sign in to Lucida (their name, the site they belong to, and when you connected them). Their sign-in keys are kept only in scrambled form.
• Your profile, if you share decks or edit it: your name, @handle, picture, and what you add about yourself.
• Your school, level, and year, if you add them: a college or university picked from a list (or typed in), and a level: high school, college, graduate, medical or professional, or other. A high school student picks the level only. Lucida has no list of high schools and keeps no high school’s name.
• If you buy Pro: whether you have it and until when. Stripe or Apple takes the payment; we never see your card number.
• Reports you send, and the people you block.
• Basic technical records. Our hosting and database providers log things like IP addresses and request times, so they can keep Lucida running and secure.

How we use it

• To run Lucida: show your cards, plan your reviews, keep you signed in, and send sign-in codes.
• To make what you ask for: cards from a file, pictures, a recording, a link, pasted text or a topic, and questions for a live game.
• To show what you share to the people you share it with.
• To keep it safe: stop abuse, look at reports, and fix problems.

We don’t sell your data, use it for ads, or use your cards to train AI models.

What others can see

A deck you share publicly, and your profile, can be seen by anyone, including search engines. A Link only deck is seen only by people with its link. Private decks are only yours.

If someone studies or copies your deck, they see it as you shared it. A copy stays theirs if you stop sharing.

Your school, level, and year show on your profile only if you turn on “Show my school on my profile”. It starts off. Nothing in Lucida lists the people at a school, and searching for a school never finds people.

A public deck can have a level, a subject, and a school. A deck’s school shows only if you keep it, and you can clear any of them in the deck’s Sharing settings. Discover uses them to narrow decks, and if you add a school to your own profile it shows you the public decks labeled with it.

AI apps you connect

When you add Lucida to Claude, ChatGPT, or another AI app, you either sign in to Lucida and press Allow, or paste your private link. That app can then read and change your cards, within what you allow on the Connect AI page. What you share with the AI app itself is covered by that company’s privacy policy.

You can cut off one app at a time with Disconnect on the Connect AI page, or every app that uses your private link at once by making a new link there. They stop working right away.

Who helps us run Lucida

• Vercel hosts the website and the app.
• Supabase stores your account, cards, pictures, and sounds, in the United States.
• Resend sends our emails.
• Stripe takes payments for Pro on the web, and Apple for Pro bought in the iPhone app.
• When you ask Lucida to explain an answer, or Learn mode asks it to write quiz questions, the card’s text, and any question you ask about it, goes to OpenRouter, which passes it to an AI model that writes the explanation, the answer or the questions. The questions you ask aren’t kept: they’re sent with that one request and nothing of the conversation is stored.
• When you ask Lucida to make cards (or live questions) from a file, pictures, a recording, pasted text or a topic, what the AI needs goes to OpenRouter, which passes it to an AI model that writes them: the text Lucida pulled out of your file, your pictures or scanned pages, or your topic. A recording goes first to a speech-to-text model, which turns it into text. We ask for services that say they don’t keep what they’re sent or train on it. They see only what you chose to make cards from, never your other cards.
• When Lucida looks for diagrams in a file you made cards from (slides, a PDF, a Word file or photos), the pictures in it go to OpenRouter, which passes them to an AI model that says which are diagrams worth studying and reads the words written in them. Logos and tiny or thin pictures are left out before anything is sent, and only the biggest few of a file’s pictures go (8 on Free, 40 on Pro). The diagrams it finds, and pictures you upload as diagrams, are kept in your own private storage and shown only to you, like a Source: never on a shared deck. A picture you upload goes to the AI, the same way, only when you ask for cards from it, to read its labels.
• When you ask Lucida to make a table or a mind map, the words of your cards, and of your notes (or only of the tag or source you chose), go to OpenRouter, which passes them to an AI model that writes it. A table or a mind map is shared with its deck, so it shows on the deck’s page if you share the deck.
• When you give Lucida a YouTube link, the link goes to Google (Gemini), which watches the public video and writes notes from it for Lucida.
• The files you upload to make cards are kept in your own private storage while Lucida works, and deleted when it’s done, unless you keep them as the deck’s Source. A file you never finish with is deleted the next time you make cards, or when you delete your data.
• Themes load their fonts from Google Fonts.
• When Lucida makes a voice for a sound card, the card’s text goes to the speech service that makes it.
• When you or your AI add a picture or sound from a link, Lucida downloads it from that site.

They only get what they need to do their part.

Cookies

We use cookies only to keep you signed in. No ad or tracking cookies.

Your choices

• Export every deck, card, and review from Settings whenever you want.
• Delete decks and cards at any time, or everything at once from Settings.
• Delete a Source to remove its file and recording (the cards stay). Deleting a deck, your data or your account removes its Sources too.
• Make a deck private again, or block someone, at any time.
• Turn off “Show my school on my profile”, or clear your school, level, or year, at any time.
• To delete your account completely, including your email address, use Delete account in Settings, or write to team@lucida.cards. Backups expire on their own soon after.

Children

Lucida isn’t meant for children under 13, and we don’t knowingly keep their information.

Changes

If we change this policy, we’ll update the date at the top. For big changes, we’ll tell you in the app or by email first.

Questions

Write to team@lucida.cards.