Privacy Policy

Soundu is for adults: you must be at least 18 to create an account. It is meant for university and adult language classes and is not designed for children. If we learn that an account belongs to someone under 18, we will delete it. If you think that has happened, tell us at binyanglc@gmail.com.

• Your account — your email address, the display name you choose, and your password — which our authentication provider stores only in scrambled (hashed) form, so nobody can read it. If you sign in with Google, we receive your name, email address and profile picture link from Google.
• What teachers make — courses, lessons, texts, word lists, pronunciation and translation lines, word meanings, and audio — generated audio and recordings of the teacher’s own voice.
• What you do in a course — how you rate words (Got it, Unsure, Not yet), words you save, dictation results, which texts you open, play and mark as read, and which words you look up while reading.
• Course membership — which courses you joined, your role in them, and who invited you.
• Study days — which days you studied, to show you your own streak.
• Built-in AI use — how many times you used the built-in AI each day, to enforce the daily limit.
• Server logs — like any website, our hosting and database providers record technical details of requests — IP address, browser type, time — to keep the service secure and working.

Pages you import from a photo or PDF are sent to the AI to be read and are not stored — they stay in your browser tab until you close it.

Some things are kept only in your browser and never sent to us:

• Your own AI keys — if you add a Gemini or DeepSeek key, it is stored in this browser only.
• Preferences — pinyin on or off, text size, reading speed, the sidebar, and similar settings.
• The voice model — teachers who generate Chinese audio download a speech model that is kept in the browser’s storage; the text is turned into audio on the teacher’s own computer.

Soundu uses only the cookies it needs: one that keeps you signed in and one that remembers whether the sidebar is collapsed. There are no advertising or analytics cookies.

• to run the site: show you your courses, save your work and progress, play audio;
• to show teachers how their class is doing;
• to send account emails, such as confirming your address or resetting your password;
• to keep the service secure, prevent abuse and enforce the built-in AI’s daily limits.

• Teachers of a course you join — the course’s creator and its co-teachers can see your display name, that you joined, and your activity in that course (word ratings, saved words, dictation results, reading progress and looked-up words). The class statistics show totals for the whole class, not a ranking of students. Teachers can’t see your study days or your activity in other teachers’ courses.
• Other students — don’t see your activity or your email address.
• Other signed-in users — may see your display name where it appears, for example in a course you share with them.
• Nobody else — courses are private to their members. We don’t publish lessons or profiles.

We would only disclose information beyond this if the law required it.

• Supabase — accounts, the database, and audio files.
• Vercel — hosting: serving the website.
• Google Gemini (built-in AI) — when a teacher uses an AI feature without their own key — importing pages, checking pinyin, translating, suggesting words, making word meanings — the text or page images are sent from our server to Google. Soundu uses Google’s free tier, under which Google may use what is sent to improve its products, and people at Google may review it. Teachers: send only material you are allowed to use, and never include personal information about students.
• Microsoft Azure (generated voices) — when a teacher generates audio for a text, its sentences are sent from our server to Microsoft’s speech service, which turns them into audio. The audio is then stored with the lesson.
• Your own AI key — if you add your own Gemini or DeepSeek key, requests go straight from your browser to that company, under your own agreement with it. DeepSeek is a company based in China.
• Google sign-in — if you choose to sign in with Google.
• jsDelivr — a public content network that serves the program files the in-browser voice generator needs.
• Your browser’s voices — sentences without saved audio are read by your device’s built-in voice. Depending on your browser and the voice you pick, the browser’s maker may process that text (for example, Chrome’s online Google voices).

These providers may store and process data in the United States and other countries where they operate.

We keep your information while your account exists. When you delete your account it is removed from our database straight away; copies can remain in our providers’ backups for a short time until those are replaced. Server logs are kept by our providers for their usual periods. Imported pages are never stored.

• Change your name — in Settings.
• Leave a course — in Settings.
• Delete your account — in Settings. This deletes your account, your progress and the courses you created, with their lessons and audio. A course that has a co-teacher is handed to that co-teacher instead of being deleted, so their class keeps it.
• Get a copy or a correction — email binyanglc@gmail.com and we will reply within 30 days.

Depending on where you live — for example in California, the European Union or the United Kingdom — you may have further rights, such as to access, correct, delete or move your information, or to object to how it is used. Email us to use them. In the EU and UK, we rely on providing the service you signed up for, and on our legitimate interest in keeping it secure, as the legal grounds for using your information; you can also complain to your local data protection authority. We do not sell or “share” personal information for advertising, as California law defines those terms.

You decide what goes into your course and whom you invite. Please don’t put personal or sensitive information about students in lesson texts, and import only material you are allowed to use with your class. If your school needs a data protection agreement before you use an online tool, contact us first.

The site is served over an encrypted connection (HTTPS), and the database checks every request so that people can only reach their own data and the courses they belong to. No system is perfectly secure; if we learn of a breach that affects your information, we will tell you.

We will post any change on this page and update the date at the top. If a change matters — for example, collecting something new — we will also tell you by email or in the app before it takes effect.

Soundu is run by an individual developer. Write to binyanglc@gmail.com with any question about your information.