๐Ÿ”’ Security & Privacy

Your data stays yours. Always.

๐Ÿ” Transport Encryption HTTPS / TLS 1.3 ยท E2E Encrypted Sync Perfect Forward Secrecy ยท MITM Protection ๐Ÿ’พ Memory-Only Processed in RAM only Released immediately No disk/log writes ๐Ÿ“‹ Data Minimization Only essential text No GPS/contacts/gallery ๐Ÿ›ก๏ธ Your Privacy Multi-Layer Security Architecture

Our Privacy Philosophy

An AI-powered keyboard has access to everything you type. We take this responsibility seriously. Langou is built on a simple principle: your data belongs to you, not us. We do not sell data, show ads, or monetize your personal information. Langou Input Method is completely free to use, with no hidden costs or data monetization.

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On-Device Processing First

Wherever possible, processing happens on your device โ€” not on our servers:

  • OCR (Optical Character Recognition): PaddleOCR runs entirely on-device. No screenshots leave your phone or computer.
  • Emotion & Intent Classification: Initial NLP analysis runs locally using TensorFlow Lite.
  • Voice Recognition: On-device speech-to-text processing via platform APIs.
  • Dictionary & Typing Habits: Your personal dictionary and learned patterns stay on-device unless you explicitly enable cloud sync.
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Cloud AI Communication

When AI reply generation requires cloud processing (the 420B parameter model is too large for on-device), here's what happens:

  • Minimal data: Only the context (up to 10 anonymized messages) is sent. No account info, device info, or location is included.
  • No storage: Prompt data is processed and immediately discarded. We do not log or store prompt contents.
  • Encryption in transit: All communication uses TLS 1.3 with perfect forward secrecy.
  • No training: Your prompts and replies are never used for model training. Period.
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Account & Sync Security

For users who enable cloud sync, we provide enterprise-grade protection:

  • End-to-end encryption: Dictionary, typing habits, and preferences are encrypted with AES-256-GCM on your device before transmission. The server stores only encrypted blobs.
  • Zero-knowledge architecture: We cannot read your synced data โ€” the encryption keys never leave your devices.
  • Two-factor authentication: Optional 2FA via authenticator app or hardware key (WebAuthn).
  • Session management: View and revoke active sessions from your account dashboard at any time.
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Accessibility & Permissions

We're transparent about the permissions Langou uses and why:

  • Accessibility Service (Android): Used only to read visible chat text when Langou keyboard is active. We never read passwords, credit card fields, or other sensitive inputs (Android's built-in security prevents this).
  • Notification Access: Optional โ€” used to detect incoming messages for proactive AI suggestions.
  • Screen Capture: Only used as OCR fallback when UI Automation fails. Capture is limited to the chat app window.
  • Internet: Required for cloud AI generation and sync. On-device features (Chinese input, offline OCR) work without internet.
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Data Deletion & Export

You have full control over your data:

  • Export: Settings โ†’ Export Data downloads all your data (dictionary, stats, preferences) as JSON or CSV.
  • Local data: Clear all local data from settings at any time.
  • Cloud data: Delete synced data from your account dashboard.
  • Account deletion: Delete your account and all associated data with 30-day grace period for recovery.
  • No data retention: We don't keep logs, analytics, or usage data. Anonymous crash reports can be disabled.

For full details, see our Privacy Policy and Terms of Service. Also check our Comparison page to see how our privacy approach differs from other IMEs.