Portfolio123 is an awesome site with so many tools Portfolio123 is an awesome site with so many tools to help investors. They are very responsive and they are often on message boards with help and will respond to emails as well.

Portfolio123 is a game-changer for… Portfolio123 is a game-changer for stock investors, providing a powerful platform for the design, simulation, and deployment of quantitative financial models. It also has stock screening, charting (including YChart style), trading (via Interactive Brokers and Tradier), macro economics charting, watchlists, an earnings center, cross-section series plotting, external data importer, a data API, stock news, stock summary snapshots, stock comparison tool, sector/Industry performance, fundamental and estimate summaries, a user forum and more (really). In the near future, machine learning will be supported. It's not just another retail-level tool; it's the only one that I’ve found to work in practice. To find something better, I suspect you'd have to go professional and spend significantly more. I've been a loyal subscriber for over a decade, which speaks volumes about its effectiveness. Is there a downside? Sure, building successful trading models is hard work, but with dedication and focus, it's possible to be successful. Whether you're researching stocks, building and simulating quantitative models, or managing accounts, Portfolio123 has what you need.

Excellent site for backtesting equity trading strategies Excellent site for testing stock and ETF trading strategies. P123 provides a thorough point-in-time database with a powerful and flexible engine to simulate backtests of systems. And they integrate with Interactive Brokers to automate applying those strategies to live trading.

Great interface and tools Great interface and tools. Hopefully the transition to the new data provider goes well.

I really like P123 works I really like P123 works. The criteria for screens are easy to create and change. It's not a dumbed down version like I've seen on other sites. The backtesting is an interesting and useful feature. To get a 5 star rating you would need to (1) change FCF to exclude dividends (that is so weird and causes me more work to get around), (2) add Invested Capital as a criteria in screening (this would also save me a lot of work), and add foreign stocks to screening universe (I wish you luck in this endeavor. At this point I cannot contribute.)