Leaf

Privacy

Leaf is a language-learning app. It keeps what it needs to teach you and nothing it doesn't. This page says exactly what that is, in plain terms.

Last updated 16 August 2026

The short version

Leaf stores your account details and your study history so your progress survives between sessions. It does not sell your data, does not show advertising, does not record your screen, and does not track you across other websites. Deleting your account deletes your data.

Who is responsible

Leaf Learning Technologies operates Leaf and is responsible for the data described here. You can reach us about anything on this page at privacy@learningwithleaf.com.

What Leaf stores

Your account

Your account is managed by Clerk. Leaf keeps a copy of your account identifier, your email address and your name, and records your time zone. The time zone matters more than it sounds: streaks, “due today” and the study heatmap are calendar-day concepts, and without knowing your zone the server would use its own and get them wrong.

Your studying

Everything Leaf keeps in this category exists to run a feature you can see:

Flashcard progress and review history. This includes each card’s scheduling state and a log of your ratings, which power spaced repetition.
Lesson, story, listening, video, roleplay, exercise and Checkpoint sessions. These record what you finished and how it went, per module.
A daily activity record. This is one counter per day and activity type. This is what draws your streak and heatmap.
Your own decks, imported decks and mined words. This includes anything you saved or imported yourself, including words tapped in stories and lessons.
Goals, placement results and dictionary lookup counts. This includes your weekly target, where the placement questionnaire suggested you start, and how often a word was looked up so the search can rank it.

Things you write

The Daily Challenge asks you to translate a sentence, and your answer is storedalong with the prompt and the result. It is kept so the day’s result and your recent history stay readable, it is retained until you delete your account, and it is never sent to analytics or written into logs. Aside from the free-text search box, which is not recorded as text, this is the only place Leaf keeps something you wrote.

Stored in your browser

Leaf uses your browser’s local storage for preferences and for one piece of housekeeping. None of it is used for advertising or shared with anyone.

Your theme (light or dark).
Roleplay volume, and whether pronunciation is shown.
Checkpoint ambience and voice settings.
Which reading system the Chinese course shows pronunciation in — Zhuyin, Pinyin, or both.
A note that you have already seen the microphone explanation in the Speak exercise, so it is not shown before every recording.
Leftovers from before Leaf had accounts: an old local copy of flashcard and Checkpoint progress, kept only so it can be imported into your account once, plus a flag recording that it was.
An identifier used to tell analytics which account is signed in.

Clerk and PostHog also set their own cookies and storage for sign-in and analytics respectively.

Who else receives data

Leaf uses a small number of services to run. Each receives only what its job requires:

Clerk — Accounts and sign-in. Your email address, name, and authentication activity. Clerk is the system of record for your account; Leaf stores a copy of your id, email and name.
Turso — Database hosting. Everything in the “What Leaf stores” section below, at rest.
Vercel — Application hosting. Standard server request data, including your IP address, while you use the site.
PostHog — Product analytics. A small allow-listed set of product events (for example “a lesson was completed”) tied to your account id, plus the pages you visit. Never lesson text, answers, search terms or your email.
Microsoft Azure — Scoring pronunciation in supported Speak exercises. Only when you record yourself in the Speak exercise: the audio of that one take, together with the line you were asked to say. Azure returns numeric pronunciation scores. Leaf keeps those scores and ordinary session details such as the lines practised and duration, but never the recording or a transcript. The audio is not kept by Leaf in any form, and does not appear in our database, logs or analytics.
OpenAI — Grading Daily Challenge answers. Only when the built-in grader cannot decide an answer: the sentence you were given and the translation you wrote. Sent with storage disabled, and not used to train models.
YouTube (Google) — Video playback in Watch and Listening. When you open a lesson containing a video, your browser streams it from Google, which means Google receives your IP address. Leaf uses YouTube's privacy-enhanced embed (youtube-nocookie.com), which Google states does not use cookies to track viewing for ad targeting. Videos are streamed, never copied or re-hosted.

Audio in the lessons is generated ahead of time and shipped as ordinary files, so playing it sends nothing anywhere. Recording yourself in the Speak exercise is the one place audio travels: that take is sent to Microsoft Azure to be scored and is then discarded. Leaf never stores your recording or a transcript of it. Leaf keeps the ordinary practice record described above: the lines you practised, session duration and the numeric scores you were shown.

What Leaf deliberately does not do

No advertising, and no selling or renting of personal data.
No session recording or screen replay. These features are switched off in the analytics configuration.
No automatic capture of everything you click. Analytics events are an explicit, reviewed list, and a filter strips anything not on it before sending.
Lesson content, your answers and your dictionary searches are never sent to analytics.

Deleting your account

You can delete your account from your account settings, which is managed by Clerk. When you do, Leaf receives a notification and automatically deletes everything listed above from its database. This includes your account record, all study history, your decks and mined words, and your Daily Challenge answers. It also deletes your analytics profile and its events from PostHog.

Two honest caveats, because “everything, everywhere, immediately” would not be true:

Backups. Encrypted database backups may still contain your data until they age out on our provider’s ordinary retention schedule. They are not used to restore individual accounts.
Clerk. Clerk holds your sign-in records under its own retention policy, which we do not control.

If you would rather not use the self-service route, or you want confirmation once it is done, email privacy@learningwithleaf.com and we will handle it by hand.

Your rights

Depending on where you live, you may have the right to access a copy of your data, correct it, have it deleted, or object to how it is used. Email privacy@learningwithleaf.com and we will respond. We will not charge you for it and we will not make the product worse for you because you asked.

Children

Leaf is not designed for children and accounts are not knowingly created for anyone under 13 years old. If you believe a child has an account, email us and we will remove it.

Changes

Leaf is in beta and still changing. If what it stores or who it shares with changes materially, this page changes with it and the date at the top moves. Substantial changes will be announced in the app rather than made quietly.