Chrome extension

Kotoba Flow Privacy Policy

Last updated: October 22, 2026

This policy describes how Kotoba Flow — Language Learning with YouTube handles information when you use the Chrome extension, including its optional connections to Kotoba Lens and supported Kotoba tools.

Kotoba Flow processes the material you study to provide lookups, translations, captions, explanations, and review. Settings and learning records are stored in your browser. Online providers receive the content needed for the features you use. Lens synchronization and usage analytics are optional.

1. Information the extension handles

• Study content: selected text, surrounding sentence or page context, captions, vocabulary, translations, readings, explanations, study progress, saved cards and loops, and messages you submit to the study assistant. Saved records can include source page URLs, titles, video identifiers, timestamps, and associated study context.
• Audio and images: audio captured when you start a listening or transcription feature, and visible-page images captured when you request image text recognition. These are used to produce study text and explanations. Capturing a page can include information visible in that image.
• Settings and credentials: language and provider preferences, API keys you enter, and connection tokens used for optional Lens synchronization. These are stored in extension storage. API keys authenticate requests to the provider you configure; they are not included in usage analytics.
• Optional analytics: if you enable usage analytics, a random browser identifier, session identifier, extension version, fixed feature event names, and limited feature/provider categories. These identifiers are pseudonymous and can associate repeated activity with the same browser.
• Network information: online services necessarily receive connection information, such as an IP address, when your browser contacts them. Lens uses network information for service operation and abuse prevention; hosting infrastructure may maintain access logs.

2. Why this information is used

Information is used to provide language-learning features: dictionary lookup, translation, reading aids, caption display, speech transcription, image text recognition, contextual explanations and chat, sentence looping, saved-material review, and user-enabled synchronization. Optional analytics measures feature usage to help improve the extension. The extension does not include advertising or sell study content.

Page access supports study features on the websites you choose. Saved source links help you reopen your study material. The extension does not request Chrome’s browsing-history permission or upload a complete browser history. Content you choose to process may itself contain personal information, so avoid submitting sensitive material you do not want a configured provider to receive.

3. Online providers and other recipients

• Dictionary and translation services: lookup terms or translation text may be sent to Jisho, MyMemory, dictionaryapi.dev, Wiktionary, or your selected translation service. Your selected provider can be OpenAI, Anthropic (Claude), Chrome’s on-device Translator, or a LibreTranslate server you configure. Dictionary requests can still use online services when translation is local. If MyMemory fallback is enabled, the complete translation input may be sent to MyMemory when the selected provider fails.
• AI features: configured OpenAI or Anthropic services receive the prompts, study context, and conversation messages needed for the feature you invoke. OpenAI is used for configured AI audio transcription and image text recognition, which can transmit audio or a captured image.
• Speech recognition: speech features use browser speech-recognition capabilities where available. Depending on the browser and configuration, recognition can be performed by a browser-provided online service. Optional AI transcription sends audio to the configured transcription service.
• Local Japanese analysis: optional Kuromoji analysis downloads dictionary data from unpkg.com and stores it locally. Text analysis then runs on your device using packaged extension code.
• Kotoba Lens: when you connect Lens, saved learning and chat records and their source metadata are synchronized with your Lens account. Authentication tokens authorize this connection. Supported local Kotoba integrations can read saved cards through the extension’s restricted bridge when you use those integrations. Disconnecting Lens stops future sync; it does not itself delete previously synchronized records.
• Google Analytics: when you opt in, limited usage events go through the Lens analytics endpoint to Google Analytics 4. Event payloads exclude study text, captions, chats, audio, page URLs and titles, account details, and API keys. Analytics is disabled by default and excludes Incognito activity.

External services handle information under their own policies and your account or server settings. See the policies for OpenAI, Anthropic, MyMemory, and Google. For a self-hosted or other configured service, consult its operator.

4. Storage, retention, and deletion

Settings, credentials, caches, downloaded dictionary data, and learning/chat records are stored in your browser’s extension storage or IndexedDB until removed, replaced, or cleared by the relevant feature, history limits, or browser controls. Extension storage is not a separate encrypted password vault. Protect access to your browser profile.

You can manage saved records in History, remove or replace API keys in Settings, delete the optional dictionary in Settings, and disconnect Lens. Uninstalling the extension removes its browser-managed local storage; it does not delete information already synchronized with Lens or retained by external providers. Manage synchronized records in Lens or request deletion through the support contact below. Provider-side retention is governed by the applicable service and account settings; this policy does not promise immediate deletion of their logs or backups.

Turning analytics off stops future event collection, clears the local analytics identity and session, and drops queued events. Turning it on again creates a new identity. Opting out does not erase events already received by Google Analytics. Lens analytics throttling identifiers are held temporarily in memory; hosting/access logs and provider records follow their respective operational retention settings.

5. Your choices

You can choose which features to invoke, select your translation provider, control MyMemory fallback, enable or disable optional AI features, leave Lens disconnected, and leave analytics off. Selecting local translation does not automatically make dictionary lookup, speech recognition, or other AI features local. You can stop audio capture through the feature’s controls and remove the extension at any time.

6. Limited Use and security

Kotoba Flow’s use and transfer of information received from Chrome APIs adheres to the Chrome Web Store User Data Policy, including its Limited Use requirements. Such information is used to provide or improve the extension’s stated language-learning purpose, not for personalized advertising, creditworthiness, or lending decisions. Transfers are limited to the uses described here and other uses permitted by that policy, such as legal compliance and security.

Hosted provider and production Lens connections use HTTPS. User-configured local services may use local HTTP connections. Keep API keys private and revoke them with the issuing provider if compromised.

7. Changes and contact

This page will be updated when the extension’s data practices change, with the update date shown above. Where required, new uses will be disclosed and consent requested before they begin.

For privacy questions or requests concerning Lens-synchronized data, use the support contact provided in Kotoba Flow’s Chrome Web Store listing. Do not include API keys in a support request.