LinguaCheck checks texts exclusively locally in your browser. No texts, usage data or telemetry are sent to the developer or to third parties.

Exceptions only on your explicit request:
1. Optional AI assistant: if you add your own API key in the settings, enable AI and agree to the data transmission, the text you process with an AI feature (AI check, rewrite, explain, AI synonyms) is sent to the provider you chose (e.g. Anthropic or an OpenAI-compatible service). That provider's privacy policy applies. The API key is stored only locally in your browser.
2. Optional online synonyms: if you enable this feature, only the single word you request synonyms for is sent to OpenThesaurus.de (German) or Datamuse (English).

Settings and your personal dictionary are stored locally in your browser. You can revoke consent to data transmission at any time in the add-on settings.