FundSim: Free browser simulator for modeling PE/VC fund lifecycles

For decades, the 'source of truth' for fund economics has been a fragile, overly complex Excel workbook. FundSim attempts to disrupt this by moving the fund lifecycle simulation—from capital calls to carried interest—into a dedicated web interface. By automating the math behind European and American waterfall structures, it removes the common 'formula error' anxiety that plagues junior analysts and students. Technically, the value proposition lies in the visualization layer. The interactive J-curve and sensitivity heatmaps transform static data into a dynamic exploration tool, allowing users to stress-test assumptions without rebuilding a spreadsheet from scratch. The inclusion of automatic progress saving and Google OAuth suggests a focus on user friction, treating financial modeling more like a modern SaaS product than a legacy accounting task. However, the tool's utility is currently capped by its positioning as an educational resource. While it is an excellent sandbox for learning fund mechanics or performing quick 'back-of-the-envelope' simulations, seasoned PE professionals will likely remain tethered to Excel for the granular control and auditability required for legal closing documents. The leap from 'simulation' to 'production modeling' is a steep one. FundSim is a strong win for finance students and VC analysts who need to visualize fund trajectories quickly. It strips away the boilerplate of spreadsheet setup, allowing the user to focus on the actual levers of fund performance. It's a practical utility that trades total flexibility for speed and visual clarity.