//LEGAL

Privacy Policy

ControlStack: AI Output Formatting
Last updated: March 31, 2026

ControlStack is a browser extension that stores UI state locally on your device. We do not collect, transmit, or sell your personal data. We do not run analytics, display advertising, or track your usage. This policy explains exactly what data the extension handles and why.

ControlStack stores the following on your device using Chrome's built-in chrome.storage.local API:

This data never leaves your device except as described in the License Validation section below. It is not transmitted to our servers, not shared with third parties, and not used for any purpose other than restoring your UI state when you open the extension.

Note on free-form text fields: Configuration fields such as custom instructions store whatever text you enter. We recommend not entering sensitive personal information into these fields. ControlStack does not read, analyze, or transmit this text — it is stored and replayed to AI platforms exactly as you wrote it, as part of the normal operation of the extension.

If you purchase a license and enter a license key, the extension sends the following information to Gumroad's servers to verify your license:

This request is made to https://api.gumroad.com/v2/licenses/verify using Gumroad's standard license verification API. This is the only outbound network request the extension makes. Once validated, the result is stored locally and the key is re-verified silently at most once per day when you open the extension.

Gumroad's handling of this data is governed by Gumroad's own privacy policy at gumroad.com/privacy.

ControlStack does not collect, store, or transmit:

ControlStack operates by modifying the content of messages you compose in AI platform interfaces before you send them. The extension reads the text you have typed in the composer input field solely to prepend your configured content block before transmission. This reading occurs locally in your browser and is not transmitted to ControlStack or any third party.

The AI platform you are using — such as OpenAI's ChatGPT or Anthropic's Claude — receives your augmented message through its normal network layer. ControlStack does not intercept, store, or transmit the content of these messages. Your interactions with AI platforms are governed by the privacy policies of those platforms.

The only third party service ControlStack interacts with is Gumroad, and only for license key validation as described above. ControlStack does not integrate with any analytics platforms, advertising networks, error tracking services, or any other third party services.

All UI state stored by ControlStack exists only in your local browser storage. You can delete this data at any time by:

We do not retain any copies of your data on our servers because we do not collect it in the first place.

ControlStack is not directed at children under the age of 13 and we do not knowingly collect any information from children. The extension has no mechanism to collect personal information from any user regardless of age.

If we make material changes to this privacy policy we will update the Last Updated date at the top of this document. Continued use of the extension after changes are posted constitutes acceptance of the updated policy. We will not make changes that result in data collection without clearly disclosing this and providing an opportunity to opt out.

If you have questions about this privacy policy or about how ControlStack handles data please contact us at:

[email protected]
controlstack.pro