Last updated: October 6, 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 stays on your device and is never sent to us. This policy describes the limited cases where data does leave your device, including anonymous statistics about how the App is used.
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 content is not transmitted to our servers as part of normal use (anonymous usage statistics, which never include this content, are described in Section 9). 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, measure how the App is used (Section 9), 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.
To understand which features are useful and where the App can be improved, we use Google Analytics for Firebase to collect statistics about how the App is used — never what you study, read, listen to, or say.
Analytics events never include the content of your flashcards or decks, deck or book names, transcripts, the words you look up, your AI prompts, or the text or audio of your IA Call conversations. They also do not include your name, email address, or payment information.
Analytics data is associated with your anonymous UID (Section 2) and a Firebase app-instance identifier, so we can understand usage over time (for example, whether people keep studying after their first week). We have configured Analytics not to collect advertising identifiers and not to use analytics data for advertising, ad personalization, or tracking you across other companies' apps or websites. We do not sell analytics data. Aggregated or individual analytics records may be exported to Google BigQuery (within our Google Cloud project) for our own analysis.
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. Usage-analytics data (Section 9) is retained for up to 14 months and then deleted automatically. 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 lingotools.cl@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 the LingoTools team at lingotools.cl@gmail.com.