Name: PredictMirror: editorial review
Rating: 3.5
Author: PredictionToolkit

What is PredictMirror?

Select an outcome and amount in the panel while browsing a supported Polymarket event. The simulator starts with a $1,000 virtual bankroll and uses current book prices with modeled slippage. Portfolio sparklines, detailed position charts and simulated fill history let you inspect entries, exits and changing paper PnL.

This Chrome/Chromium extension stores the practice portfolio locally. Clearing local extension data can remove the record, and resetting the bankroll begins a separate experiment rather than demonstrating realized performance. The current advertised venue is Polymarket; Kalshi and Manifold are coming soon. Simulated fills never submit an exchange order and cannot establish the result of live execution.

Who it is for

New users learning how outcome prices affect PnL.
Traders practicing discretionary entries with virtual capital.
People who prefer to keep practice history in their browser.

Features and coverage

Panel beside the event
Open the paper simulator next to a supported Polymarket event page.
Virtual bankroll
Begin with $1,000 and reset the balance when starting a new experiment.
Current-price simulation
Use current order-book prices with the product’s modeled slippage, rather than sending an exchange order.
Position charts
Follow paper PnL with portfolio sparklines and detailed charts.
Simulated fill history
Inspect the entries and exits that created each practice position’s result.
Open and closed positions
Separate active simulated exposure from realized practice results.
Practice indicators
Review win rate and streak measures over the stored practice record.
Local portfolio
Keep the portfolio in browser storage without creating a remote account.

Workflows with PredictMirror

Practice an event trade

Open the market, choose a side and amount in PredictMirror, record the simulated position and follow its PnL as prices change.

Compare approaches

Keep the virtual bankroll and sizing/exit assumptions consistent. Reset only when starting a separate experiment.

Review completed practice

Filter closed positions and inspect fill history to see which entries and exits produced the outcome.

Pricing and total cost

The website advertises free access without an account requirement.

Getting started

Before you start: Kalshi and Manifold support is planned rather than current.

Follow the official Add to Chrome link.
Open a supported Polymarket event page.
Check the virtual balance in the PredictMirror panel.
Choose an outcome and amount and submit a paper trade.
Inspect open positions and simulated fill history.
Retain the browser profile’s local data to preserve your practice record.

Polymarket is the advertised current venue; Kalshi and Manifold remain marked coming soon.

Useful links

What to check

Kalshi and Manifold support is planned rather than current.
Modeled fills do not send exchange orders.
Clearing the extension’s local data can remove the stored portfolio.
A bankroll reset begins a new practice comparison and is not realized trading performance.

A closer look

Ratings & reviews

Editorial rating

3.5/ 5

0 user reviews

PredictionToolkit editorial

Our take on PredictMirror

An in-page virtual balance, charts and local history make this approachable for practice. Modeled slippage and alternative venues that remain planned limit what the simulation establishes about real trading.

Based on documented features, setup and access terms. How we rate