Last updated: August 29, 2026
This Privacy Policy explains how Diego Rios Rojas ("we", "us") handles information in connection with the LingoTools mobile application (the "App"). LingoTools is an offline-first language-learning app: the large majority of your content and activity stays on your device and is never sent to us. This policy describes the limited cases where data does leave your device.
Your study sections, decks, flashcards, imported books/podcasts, reading and listening progress, spaced-repetition schedules, and app preferences are stored locally on your device (in the app's local storage and file system). This data is not transmitted to our servers as part of normal use. Deleting the App removes this local data.
When you first open the App, it automatically signs in anonymously to Firebase Authentication (a Google service) and receives a random anonymous identifier (a "UID"). This requires no name, email, or password. The UID lets the App access network-dependent features (below), enforce fair-usage limits, and associate any cloud backup with your install. It does not, by itself, identify you personally.
Signing in is optional and is offered only so a cloud backup can survive a reinstall or move to a new device. If you choose to sign in with Sign in with Apple or Google Sign-In, we receive the basic profile information the provider returns (such as your name and email address, subject to your choices — for example, Apple's Hide-My-Email option) and use it to link your anonymous identity to a permanent account. If you never sign in, we do not collect your name, email, or Google/Apple account details.
In the Books tab you can play podcasts and audiobooks and generate synchronized transcripts. Short audio is transcribed on your device and never uploaded. For longer audio, a premium server process downloads the publicly available audio and transcribes it using a third-party speech-to-text provider.
Transcripts are stored in a shared cache keyed by a cryptographic hash
(SHA-256) of the audio, at transcripts/<hash>.json. Because the key is
derived from the audio itself and the cache is content-based, a transcript produced for a
given audio file may be reused by other users who play the same file, and a transcript
produced on your device may be uploaded so others benefit. Transcripts contain the spoken
text of the audio, not personal information about you. During server transcription, the
audio and interim upload artifacts may be stored temporarily under
transcribe_uploads/<uid>/.
Some features send text or audio you provide to third-party AI providers to generate a response. This includes deck-generation topics, AI deck enrichment prompts, and the "IA Call" conversation-practice feature. When you use IA Call, your microphone audio for that conversation is processed to produce a spoken reply. We use the following providers as processors for these features:
We send only what a feature needs to work (for example, your prompt or the relevant audio), and content you submit is treated as untrusted input and isolated before processing.
Premium subscriptions are processed through RevenueCat and the Apple App Store. RevenueCat manages your subscription/entitlement status; its app-user identifier is linked to your Firebase UID so the App knows whether Premium is active. Payment and billing are handled by Apple — we do not receive or store your payment card details. We receive subscription status (active/expired, plan, renewal anchor) to unlock premium features and apply usage limits.
The App shows ads through Google AdMob (Google Mobile Ads). AdMob may use advertising identifiers and similar technologies to serve and measure ads. Where required (for example, users in the EU/EEA under GDPR, and on iOS via App Tracking Transparency), the App presents a consent prompt through Google's User Messaging Platform before personalized ads are served; if consent is not given, ads are served in a non-personalized mode. Premium subscribers do not see ads. See Google's advertising and privacy policies for details on how AdMob processes data.
We rely on the following service providers:
Local data remains on your device until you delete it or remove the App. Server-side data (anonymous account, shared-cache transcripts, temporary transcription uploads, usage/quota records, and any cloud backup you create) is retained for as long as needed to provide the relevant feature and to meet legal or operational requirements. Shared-cache transcripts are content-based and not tied to your identity. When you delete your account (see below), data associated with your account is removed as described.
LingoTools is not directed to children under the age of 13 (or the minimum age required in your jurisdiction), and we do not knowingly collect personal information from them. If you believe a child has provided us personal information, contact us at d.riosrojas007@gmail.com and we will take appropriate steps to delete it.
Our service providers may process and store data in countries other than yours, including the United States. Where required, we rely on appropriate safeguards for such transfers. By using the App, you understand that your data may be processed in these locations.
We may update this Privacy Policy from time to time. When we do, we will revise the "Last updated" date above and, where appropriate, provide additional notice. Continued use of the App after changes take effect constitutes acceptance of the updated policy.
Questions or requests regarding this policy? Contact Diego Rios Rojas at d.riosrojas007@gmail.com.