Proofmark

Privacy Policy

Last updated: October 1, 2026. Publisher: CHPX. Contact: support@chpx.io.

What Proofmark does

Proofmark is a browser extension that checks the spelling and grammar of text you choose, and can rewrite it on request.

When Proofmark reads your text

Proofmark only runs when you ask it to: by pressing its keyboard shortcut, choosing "Check with Proofmark" from the right-click menu, or clicking its toolbar button. It then reads the text you selected, or the text box you are typing in, on that page only. It does not read pages in the background and it does not see anything you have not asked it to check.

How your text is processed

The text you check is sent over an encrypted connection to our server at proofmark.chpx.app, which passes it to OpenAI's API to find mistakes or produce a rewrite, and returns the result to you.

• We do not store the text you check, and we do not write it to logs.
• OpenAI processes the text to produce the result. Under OpenAI's API terms, data sent through the API is not used to train their models and may be kept for up to 30 days for abuse monitoring before it is deleted. See OpenAI's privacy policy.
• Avoid checking passwords, payment details or other secrets.

What we keep

• A random identifier for your installation, stored as a hash, and a daily count of how many checks it used, to apply the free limit. Counts expire after two days.
• A hashed version of your IP address with a daily count, used only to stop abuse of the free plan. It also expires after two days.
• If you buy Pro, your purchase status and a Stripe customer reference.

Payments

Payments are processed by Stripe. Your card details and email are entered on Stripe's page and handled under Stripe's privacy policy.

Anonymous usage statistics

Proofmark sends a few anonymous events (for example "a check was run") to Plausible Analytics, a cookieless service. These events never contain your text, the page address or anything that identifies you. You can turn them off in the Proofmark popup.

What we do not do

• We do not sell or share your data.
• We do not use your text for advertising or to train AI models.
• We do not run any remote code in the extension.

Your rights (GDPR / LGPD)

You can ask for access to, or deletion of, any data we hold about you by writing to support@chpx.io. Uninstalling the extension removes everything stored in your browser.