Cleodora is free and open source software. You can use it to track personal forecasts and, by getting feedback on your performance, systematically improve at making such predictions/forecasts.
Cleodora is a web application that you can download to your computer and then access via your web browser. It requires no setup (single binary) and runs on Microsoft Windows, macOS and Linux.
For example you can forecast “Will I increase my salary by 20% within the next 24 months?”. You predict “Yes” with a confidence of 60%. As the months pass you keep adjusting your confidence up and down depending on new information you get (quarterly sales figures, feedback from the boss, inflation). Every time you adjust your prediction, Cleodora will ask you to justify why you are doing it.
After 24 months have passed you realize your salary only increased by 12%, so you resolve your forecast as “No”. Cleodora will then tell how how accurate your forecasts were over time and you can analyze your reasoning for adjusting up or down. In the future you will then avoid some of the pitfalls that made you inaccurate in your predictions.
Cleodora is not a prediction market. A prediction market tries to maximize profits for individual forecasters. At the same time the aggregated knowledge of all the traders is reflected in the market and make this market a very accurate forecast in itself.
Cleodora is specifically for improving your own forecasts. Training this ability is something you could then use to make profits in a prediction market.
Later versions of Cleodora will support making forecasts publicly or within a group to hold forecasting competitions where everyone is competing to make the most accurate forecasts on the same issues. The main use case will always be making personal, private forecasts and systematically improving at making them.
To install and run Cleodora have a look at the user documentation.