A tip of a great tool.
Open solver is an Excel addin. It is very similar to the MS solver. The difference is that the default solver has a limit of around 5000 variables. Above this, the user has to purchase the Frontline solver (the name of the company).
Page: https://opensolver.org

To use opensolver, just download, unpack and add it to the Excel supplements.
A good evolution of openSolver is solverStudio, from the same developer. It allows a formulation of the problem using formulas, supports more optimization languages and is faster. But it is also a bit more complex to deal with.
Solver studio https://solverstudio.org
Both of these tools are able to use any solver. The package comes with CBC, the great open source solver from COIN-OR. https://www.coin-or.org/
Frontline solver:
Ideias técnicas com uma pitada de filosofia