USTChEX: A free numerical solver addin for MS Excel

Originally developed under Project XLSLANI and first released through Allan’s Stuff (now defunct), this Excel add-in was built to fill a long-standing gap in spreadsheet computation. Excel’s built-in toolset lacks many of the core numerical methods needed in engineering analysis—such as surface interpolation, numerical integration, ordinary differential equation (ODE) solvers, and multi-variable system solvers.

The USTCHEX version continues that work, providing an expandable library of numerical procedures and specialized chemical-engineering functions directly accessible from Excel formulas. While this section is still relatively barebones and under active development, future updates will broaden its scope to include more robust solvers, advanced thermodynamic routines, and shortcut calculations for complex process problems..

Download the add-in here (via MediaFire)
CURRENT VERSION: v1.1 (December 2025 release)