Privacy Policy

• Phone number — required to create an account and verify your identity via one-time password (OTP).
• Display name — chosen by you during onboarding or in settings.
• Profile picture — optional image you upload; stored on Amazon Web Services (AWS) S3.
• About text — an optional short bio visible to your contacts.

With your permission, Langu reads the phone numbers stored in your device's contacts list and sends them to our servers to identify which of your contacts also use Langu. Phone numbers that do not match a Langu account are used only for this matching process, are discarded immediately afterwards, and are never stored. We retain only the phone numbers of contacts who are Langu users so we can show them to you as suggested connections. You can decline contacts access and still use the app.

If you block another user or report a user or content, we store your block list and the report you submit (including the reason you select and any message content you reference) so we can enforce our Terms of Service and keep the platform safe.

All messages you send and receive through Langu are stored on our servers to provide the chat service, enable message delivery to recipients who are temporarily offline, and support real-time translation. A message stays on our servers for as long as the chat it belongs to exists; it is deleted when its sender deletes it for everyone, which the app allows for 48 hours after sending, within 30 days of that request and including residual copies in our backups. A copy also remains on the devices it was delivered to, in the app's local storage (SQLite), until that person uninstalls the app or deletes the chat.

Langu lets you record and send voice messages. With your permission, the app uses your device's microphone to record audio while you hold the record button. You can decline microphone access and keep using the rest of the app — only recording is disabled. Here is exactly what happens to a recording:

• It is uploaded and stored. When you send a voice message, the audio file is uploaded to our media storage (Amazon S3) and kept there so the people in the chat can play it. Recordings are limited to 10 minutes and 10 MB. Playback uses a long, randomly generated link that is not listed or indexed anywhere — but anyone who obtains that link can play the recording.
• It is transcribed when a recipient unlocks it. A voice message is not transcribed automatically. If a recipient chooses to unlock the transcript, we send the audio file to OpenAI, which converts the speech to text. We store the resulting transcript on our servers and reuse it for anyone else in the same chat who unlocks the same recording, so the audio is sent for transcription only once.
• The transcript is translated. The transcript is then sent to Google Cloud Translationto be translated into the recipient's learning language for that chat. Transcripts and their translations are stored on our servers so the same text is not sent to the provider again.
• We record who unlocked what.We store which of your voice messages each user has unlocked and when, so a repeat unlock is free and does not consume the user's quota.
• Deletion.Deleting a voice message for everyone — which the app allows the sender to do for 48 hours after sending — deletes the audio file from our media storage, together with its stored transcript and translations. That removal completes within 30 days, including residual copies in our backups. A copy of the audio may remain in the app's local cache on devices it was already delivered to.

We do not use your recordings, transcripts, or messages to train AI or speech models, and we do not use them for advertising or profiling.

We store your chosen interface language, your fluent language, and fluency signal data (e.g. messages read and written per day) to provide the fluency tracking and progress features. This data is retained as long as your account exists.

We collect your device's Expo push notification token to send you message notifications. This token is associated with your account and updated each time you log in. When you are offline and a message arrives, the notification we send through the Expo Push Notification Service contains the sender's display name and the text of the message, so that it can be shown on your lock screen. You can disable notifications at any time in your device settings.

If you purchase a Plus or Pro subscription or a boost pack, we record your subscription tier, purchase date, expiry date, and usage quotas. Payment processing is handled entirely by Stripe or the Apple App Store / Google Play — we do not store your card number, bank details, or any payment instrument data.

Our servers automatically log standard technical information when you use the app, including IP address, device platform (iOS or Android), and timestamps of API requests. This data is used for security, fraud prevention, and debugging.

• Your account record: phone number, display name, profile picture, and about text.
• The media you uploaded — your profile picture file, and the photos and voice recordings attached to messages you sent, including messages that stay in an archived chat — together with the transcripts and translations we had stored for those recordings.
• Your saved contact matches — the Langu users we had linked to your account.
• Your language settings, fluency signals, and progress data, including the grammar explanations and conversation suggestions generated for you.
• Your push notification token, so no further notifications can be sent to you.
• Your record of which voice messages you had unlocked.
• The AI writing corrections and translation revisions saved alongside your messages — both the ones you applied yourself and the ones someone else applied to a message you wrote — together with any suggestions that were previewed but never applied, whoever asked for them.
• Your billing and subscription records held by Langu. Any active Stripe subscription is cancelled as part of the deletion.

• Your one-to-one chats are archived and your messages stay in them, no longer linked to your account. The people you talked to keep the conversation they took part in, exactly as they would if you had simply left the chat. This is a deliberate choice, and it draws a line between your words and your files: the messages you sent may stay visible to the other people in those archived chats, but the media you uploaded — photos, voice recordings, and your profile picture — is deleted from our servers. If you owned a group chat, ownership passes to the longest-standing remaining member.
• Copies on other people's devices.Messages and voice recordings already delivered to other participants remain in their app's local storage on their devices, and we cannot remove them.
• A deletion audit record. We keep the deletion timestamps and a one-way cryptographic hash of your phone number — not the number itself — as proof that the deletion was carried out.
• AI processing cost records. The internal records of what the translation and AI features cost us are kept for accounting, with your user and chat identifiers removed so they no longer identify you.
• Payment records held by payment providers. Stripe, the Apple App Store, and Google Play keep their own transaction records under their own policies and legal obligations. We cannot delete those on your behalf.