ToneSync — Privacy Policy
Last updated: June 5, 2026
ToneSync (“the extension,” “we,” “us”) is a Chrome extension published by Sun Ventures. ToneSync stores everything locally in your browser and connects directly to Anthropic's Claude API using your own API key. We operate no servers and collect nothing.
What's stored on your device
Your Anthropic API key, your voice fingerprint (built from the writing samples you provide), your rewrite history (up to your last 50 rewrites), your monthly usage counts, and your settings are stored locally in your browser using Chrome's built-in storage. We never receive any of it.
How analysis & rewriting work
ToneSync requires your own Anthropic API key (a free key from console.anthropic.com). When you train your voice or rewrite text, the relevant text is sent directly from your browser to Anthropic's Claude API using your key, and the result is returned to you.
- This traffic does not pass through any server operated by Sun Ventures — we don't have one, and we never see your text or your key.
- Your use of the Claude API is governed by your own agreement with Anthropic. Per Anthropic's API terms, content sent through the API is not used to train Anthropic's models.
Gmail & LinkedIn
ToneSync's drift indicator reads the text you are actively composing in Gmail and LinkedIn so it can compare it against your voice fingerprint and, when you choose, rewrite it. This is processed on your device or via the Claude API call described above. ToneSync does not read or collect anything else from those sites, and sends nothing to us.
What we collect
Nothing. ToneSync has no accounts with us, no analytics, no advertising, no third-party trackers, and no servers operated by us.
Children's privacy
ToneSync is not directed to children under 13 and does not knowingly collect personal information from them.
Changes
We may update this policy from time to time; the date above reflects the latest version.
Contact
Questions? Email me.