SSAP — Slope Stability Analysis

SSAP computes a factor of safety for a slope using the established limit equilibrium methods — Morgenstern-Price, Spencer, Janbu, Bishop — and searches automatically for the critical slip surface, including non-circular surfaces. It handles soil layers, groundwater level and pore pressures, external loads, anchors and retaining walls, and pseudo-static seismic analysis.

It is one of the very few free tools in this field that reaches the coverage of commercial packages, developed in academia and maintained continuously for years. The output includes a report and graphics you can attach to a submission.

What is missing: it runs on Windows only, and the interface is not modern. The usual rule applies — the result is sound, the design check must follow your own standard.