Privacy Policy

Last updated: March 18, 2026

Castwyn is designed with privacy in mind. Your audio and transcripts stay on your device unless you explicitly choose to use cloud features.

On-Device Transcription

The default transcription mode runs entirely on your Mac using WhisperKit. No audio data leaves your device. The speech recognition model is downloaded once and stored locally.

Cloud Transcription (Optional)

If you enable cloud transcription in Settings and provide your own OpenAI API key, audio files are sent to OpenAI's servers for transcription. This only happens when you explicitly select "Cloud (OpenAI API)" as the transcription engine. Refer to OpenAI's privacy policy for how they handle data.

AI Transcript Improvement (Optional)

If you use the AI improvement feature, transcript text is sent to either Anthropic or OpenAI, depending on which provider you select. This only happens when you explicitly click "Improve" on a transcript. Refer to Anthropic's privacy policy and OpenAI's privacy policy for how they handle data.

API Keys

API keys you enter in Settings are stored locally on your device in application preferences. They are only transmitted to the respective API provider when making API requests. They are never sent anywhere else.

Data Storage

All transcripts, settings, and downloaded models are stored locally in the application's sandboxed storage on your Mac. Nothing is synced to any external server.

Analytics and Tracking

Castwyn does not collect any analytics, usage data, crash reports, or telemetry. There are no user accounts and no sign-in.

Contact

If you have questions about this privacy policy, please contact us at [email protected].