PredictMirror
Add to Chrome

Privacy Policy

Last updated · May 18, 2026

PredictMirror is a paper-trading simulator. We built it so traders can practice prediction markets without risking real money — and without giving up their data. This policy is organized in two parts: how the extension handles your data (it stays in your browser), and what the marketing website at predictmirror.com collects (standard web analytics).

1. Summary

PredictMirror is a browser extension that overlays a simulated trading interface on top of Polymarket.com. The extension stores your virtual balance, simulated positions, and preferences entirely within your own browser. No PredictMirror server holds your trading data. There are no accounts, profiles, or user IDs. The extension does not track you across the web.

If you stop using PredictMirror, deleting the extension also deletes everything it stored.

The marketing website at predictmirror.com — separate from the extension itself — uses Google Analytics to understand how visitors find the site. See section 7 for full details and opt-out instructions.

2. Data the extension collects

The PredictMirror extension collects only the information required to run the simulator on your machine. All of the following lives in your browser's local storage and never leaves your device:

  • Virtual balance — your current paper-trading balance and the total starting balance.
  • Simulated positions — open and closed paper trades, including the market, side, amount, fill price, and timestamps.
  • Trading statistics — derived values like win rate, current streak, and unrealized/realized P&L.
  • Preferences — UI settings such as accent color, panel position, density, and notification toggles.

This data is owned by you. It is not transmitted to PredictMirror, to Polymarket, or to any third party.

3. Data the extension doesn't collect

To be explicit about what the extension doesn't do:

  • It does not collect your name, email address, phone number, or any other contact information.
  • It does not collect your IP address, location, device identifiers, or browser fingerprint.
  • It does not collect your Polymarket account information, wallet addresses, or any on-chain activity.
  • It does not collect analytics, telemetry, error reports, or usage data of any kind. (The marketing website is separate — see section 7.)
  • It does not maintain user accounts. There is nothing for you to sign in to.

4. Where extension data is stored

All data the PredictMirror extension creates is written to the browser's chrome.storage.local API. This is a sandboxed key-value store scoped to the extension and your browser profile. It does not sync to your Google account, and it is not visible to other extensions or websites.

You can clear PredictMirror's stored data at any time by using the in-extension "Reset balance" control, or by removing and reinstalling the extension. Uninstalling PredictMirror permanently deletes all of its locally stored data.

5. Chrome permissions

PredictMirror requests the minimum permissions necessary to function:

  • storage — required to persist your virtual balance, positions, and preferences across sessions.
  • host access to polymarket.com — required to read live market data from Polymarket's public pages so that your simulated trades reflect real prices. The extension only activates on Polymarket pages.

PredictMirror does not request access to your tabs, browsing history, downloads, clipboard, or any other browser surface.

6. Third parties

PredictMirror integrates with the following third-party services. We have no relationship with their corporate parents beyond using their products; this list exists so you can make an informed choice.

Polymarket

To display live market prices, the extension reads publicly available data from Polymarket's website (polymarket.com and its public APIs at gamma-api.polymarket.com and clob.polymarket.com). This is the same data your browser would request anyway when viewing those pages. The requests originate from your browser and are subject to Polymarket's privacy policy.

Google Tag Manager and Google Analytics 4

The marketing website at predictmirror.com (not the extension) loads Google Tag Manager, which in turn loads Google Analytics 4. These services are governed by Google's privacy policy. See section 7 for what they collect and how to opt out.

Google Search Console

Used to monitor how predictmirror.com appears in Google Search. Verification happens via a static meta tag and Google's crawler — no runtime scripts or cookies are added to the site for this purpose.

Formspree

Receives the optional uninstall feedback form at predictmirror.com/uninstall/. Submission is voluntary and collects only your selected reason and any comments you type — no email or identifying information. Submissions are handled under Formspree's privacy policy.

Web hosting

predictmirror.com is served by a third-party web host. As with any web host, the hosting provider's servers may keep standard request logs (IP address, timestamp, user-agent) for operational and security purposes. We do not use these logs for tracking or profiling.

7. The predictmirror.com website

This section covers the marketing website at predictmirror.com — separate from the extension itself, which collects nothing (see sections 2–4).

Analytics

We use Google Analytics 4, loaded via Google Tag Manager, to understand how visitors find and use the site. GA4 collects standard web-analytics signals: pages viewed, referring URLs, device type, browser, and approximate geographic location derived from a truncated IP address. GA4 stores cookies in your browser (typically named _ga and _ga_*) with a default lifetime of up to two years; Google may aggregate this data across other Google services per their privacy policy.

You can opt out of Google Analytics at any time by:

  • Installing the official Google Analytics opt-out browser add-on.
  • Blocking Google Tag Manager with a privacy-focused browser, content blocker, or tracker-blocking extension.
  • Clearing cookies for predictmirror.com between visits.

Opting out of website analytics has no effect on the PredictMirror extension — the extension never communicates with Google in any form.

Search Console

Google Search Console is used purely to monitor indexing in Google Search. It does not load runtime scripts on the site and does not set cookies on your browser.

Uninstall feedback

If you uninstall the extension, Chrome opens a feedback page at predictmirror.com/uninstall/. Submitting the form is entirely optional; closing the tab sends nothing. Submissions are transmitted to Formspree, which forwards the contents to us. The form does not request your name, email, or any identifying information.

Advertising

We do not serve ads on predictmirror.com and we do not load ad-network scripts. Google Analytics is configured for visitor measurement, not for advertising or remarketing.

8. Children's privacy

PredictMirror is intended for users 18 and over. Prediction markets — even simulated ones — involve concepts that are not appropriate for minors. We do not knowingly collect data from anyone under 18, and because we do not collect personal information at all, we cannot identify users by age.

9. Changes to this policy

If we ever change this policy, we will update the "Last updated" date at the top of the page and post a notice on the extension's release notes. Material changes will be communicated within the extension itself so you can review them before continuing.

10. Contact

If you have any questions about this policy or how PredictMirror handles data, reach out at contact@predictmirror.com.