Legal

Privacy Policy

Last updated: September 29, 2026

The short version

• Your audio files never leave your device by default. Transcription runs inside your browser. The only exception is the optional Pro "Audio backup" feature, which is off by default and uploads your files only to your own private cloud storage when you explicitly enable it.
• If you have an account, your practice data (progress, transcribed text, saved sentences and words) syncs to our servers so you can continue on any device. You can turn this off anytime in your dashboard.
• We don't sell or share your data with advertisers. Ever.

What stays on your device

Audio files you upload are read, transcribed, and played entirely in your browser (WebGPU/WASM). The audio bytes are stored only in your browser's local storage (IndexedDB) so you can resume without re-processing. They are never transmitted to our servers; the only way audio leaves your device is the opt-in Pro Audio backup described below.

What we collect

Account information

When you sign up we store your name, email address, and (for email accounts) a hashed password. Google sign-in shares your name, email, and profile image with us.

Practice data (cloud sync, signed-in users)

To make your practice portable across devices, we sync: practice progress and scores, the transcribed text of files you process (sentence text and timestamps — not the audio), and your review notebook and word notebook. This data is private to your account, compressed, and never shared. You can disable sync per device in your dashboard; when disabled, everything stays in that browser only.

Audio backup (Pro, opt-in)

If you enable Audio backup in your dashboard, your uploaded audio files are stored in private cloud storage (Cloudflare R2) under a key only your account can access, so your own materials follow you across devices. Files transfer directly between your browser and the storage provider; they are never shared, published, deduplicated across users, or accessible to anyone but you. Turning the feature off stops new uploads; deleting a practice file deletes its backup.

Payments

Payments are processed by Stripe. We never see or store your card details; we store your subscription status and a Stripe customer reference.

Usage analytics

We use Google Analytics to understand aggregate feature usage (e.g., how many people try the demo). Signed-in activity can be associated with a pseudonymous account ID. We do not send Google Analytics your email, audio, or practice answers.

To understand what leads to sign-in, we temporarily keep a limited recent activity trail in your browser tab. A summary of the previous 30 minutes can be attached to a sign-in event. Recorded usage includes page categories, feature actions, sign-in prompts, material source, public Library IDs, and numeric practice scores—not uploaded filenames, audio, transcripts, typed answers, AI questions, or full URLs. This sign-in journey tracking respects browser Do Not Track and Global Privacy Control signals. Tab-local authentication context expires after one hour.

When configured, PostHog processes these limited product events, including before sign-in, using a random identifier stored in first-party cookies and browser local storage. We do not generate a hardware fingerprint. We disable IP-based geolocation enrichment, automatic interaction capture, session replay and recording of your input content. Signing in associates that browser's previous anonymous activity with your account. Signing out or changing accounts starts a separate visitor identity. Clearing cookies or using another browser can break continuity. PostHog cookies are configured with a 90-day expiry; this is not a server-data deletion period. Analytics retention is managed separately in our PostHog project. Turning analytics off stops future collection; it does not erase previously saved records. Contact us to request deletion of account-linked analytics as well as application data.

Third-party services

Word lookups are sent through our server to Dictionary API or Datamuse, and word translations are sent through our server to a translation provider. These requests contain the word being looked up but not your account identity. Library audio may be fetched directly by your browser from its publisher (including VOA, archive.org, and NASA/megaphone CDNs). These requests are governed by those services' own policies. Your practice audio is never part of such requests.

Data retention & deletion

Synced practice data is kept while your account exists. Deleting your account removes all synced records. To delete your account or request an export, email contact@listenslice.com — we action requests within 30 days. Local data can be removed anytime by clearing your browser's site data.

Cookies

We use a session cookie to keep you signed in (NextAuth) and Google Analytics cookies for aggregate usage measurement. When configured, PostHog uses first-party cookies and local storage for product analytics as described above. No advertising or cross-site tracking cookies.

Changes

If this policy changes materially we'll update this page and the date above. Questions: contact@listenslice.com.