XSLOPE — free, open-source slope stability analysis software
Limit equilibrium, finite element seepage, and finite element strength reduction — three analysis modes driven from one problem definition, in a desktop application for macOS and Windows and a Python package you can script. Verified against more than 800 published benchmark cases, and free under the Apache 2.0 license.
No license fees, no seat count, no license server · macOS 11+ (Apple silicon) and Windows 10 / 11 · Install guide · source on GitHub
Three analysis modes, one model
A defensible slope analysis needs three things: a seepage solution for the pore pressures, a limit equilibrium factor of safety, and — increasingly — a finite element strength reduction check that finds the failure mechanism without an assumed surface. Commercial suites sell those as separate modules. XSLOPE runs all three from a single problem definition: enter the geometry, materials and water conditions once, and the computed pore pressure field passes straight into both stability analyses, on the same mesh, with no re-meshing and no manual transfer.
The Johnson Reservoir dam, analyzed three ways from one input file. Every panel is drawn by the same plotting functions the package ships, and every number on it is computed by the run that produced the figure — see the worked example.
What you get
Limit equilibrium
Seven methods — OMS, Bishop, Janbu, Corps of Engineers, Lowe & Karafiath, Spencer and Morgenstern–Price — with automated circular and non-circular critical surface searches, reinforcement, piles, seismic loading and rapid drawdown.
Finite element seepage
Saturated and unsaturated flow, steady state or transient, confined or unconfined, with anisotropic materials, three unsaturated conductivity models and flow nets — usable on its own as a 2D groundwater program.
Finite element stability
Shear strength reduction with an elastic–perfectly-plastic Mohr–Coulomb model, so the critical mechanism emerges from the stress field instead of being assumed, on the same mesh and pore pressures as the seepage run.
Reliability and parametric studies
Monte Carlo and Taylor-series probability of failure, one-at-a-time sensitivity curves, tornado and spider plots, design solves for a target factor of safety, and back-analysis of an observed failure.
Works with your existing files
Reads and writes GeoStudio SLOPE/W projects, imports Rocscience Slide2 and RS2 models, and exchanges geometry with CAD through DXF — so you can migrate your existing projects outright, or run XSLOPE alongside them as a second opinion.
A desktop app for Mac and Windows
XSLOPE Studio is a simple, intuitive graphical interface — build, mesh, analyze and plot without writing a line of code. Native installers for both platforms, no Python required, updates built in — including the Mac, where the commercial suites don't go.
An AI assistant, built in
Hand it a sketch or describe the problem, and the assistant builds the input file; ask, and it runs the analyses and interprets the results — with the verified solvers doing all the computing. It's also a tutor: ask about the underlying equations, how pore pressures affect stability, or whether XSLOPE can handle your case, and it answers like an instructor. Bring your own API key for Claude, GPT and other models. No commercial package has anything like it.
A real Python API
Every solver is a callable function on a pandas DataFrame. Loop it for parametric sweeps and reliability, drive it from a notebook, run it in Colab, or let an AI agent orchestrate it.
Verified against the manuals practitioners already trust
Rather than a handful of textbook cases, XSLOPE is checked problem by problem against the published verification manuals of the major commercial codes — the Rocscience Slide2, Slide2 groundwater and RS2 manuals and the GeoStudio SLOPE/W manual and SEEP/W examples — alongside classical closed-form solutions. More than 800 cases are checked by an automated regression suite that re-runs on every change, and every comparison is published here, problem by problem, including the ones where XSLOPE and the vendor disagree.
Inspect every verification case →
XSLOPE Studio — a desktop application for macOS and Windows
Studio brings the whole engine into a point-and-click workflow. Open an Excel problem and see its geometry rendered; edit any input through forms, tables, or by double-clicking a feature on the canvas; build a mesh; run limit equilibrium, seepage and finite element analyses; and review results across dedicated views — without writing a line of code. It installs from a single download, with no Python setup of any kind, and updates itself.
See Install for system requirements and first launch, and the XSLOPE Studio section for a tour of the interface, editing, and running analyses.
An AI assistant inside the application
Building the input file takes much of the time in routine practice. Studio's built-in assistant builds it from what you already have: paste a photograph of a hand sketch, a figure from a report, or a CAD export, and it reads the geometry, materials, water conditions and loads, writes the input file, runs the analysis, and explains the result. It can also drive the engine — "vary the slope angle from 20° to 30° and plot the factor of safety", "why did the strength reduction run not converge?" — because the engine underneath is a scriptable library.
It is also a tutor — ask it a question instead of a task:
"Why does raising the water table lower my factor of safety?" — effective stress worked through on a single slice, numbers and all.
"Can I run Bishop on a non-circular surface?" — no, and the reason why, checked against the solver rather than guessed.
"How do I model a tieback wall?" — where the capacities go, with links to worked problems verified against published results.
Every answer can cite this documentation — links open in your browser — and the example problems it points you to come with published verification.
The assistant sets up and orchestrates; the analysis itself is done by the same verified solvers, so results are never invented. See AI Assistant for what it can do, and the portable Claude Code skill for the same workflow outside Studio.
Free and open source
Commercial slope stability suites are typically licensed per seat at roughly $10,000–$20,000 per year, and the source code behind a result cannot be inspected. XSLOPE costs nothing, runs on as many machines as you like, and every algorithm — and every verification case behind it — is open to inspection, audit and extension.
XSLOPE is released under the Apache License 2.0, a permissive license that allows commercial and private use, requiring only that copyright and license notices be preserved. It grants express patent rights and permits derivative works under different terms. The intent is straightforward: remove both the cost barrier and the code barrier for students, researchers, and practitioners — including those in under-resourced regions — while keeping the methods open to the community that relies on them.
The Python package
The same engine is a Python package on PyPI, with source on GitHub:
pip install xslope
Scripts and notebooks call the same solvers, meshers and plotting functions that Studio calls, and read and write the same Excel problems — so a model can be built in Studio and swept in a notebook, or the reverse. This makes parametric sweeps, Monte Carlo reliability studies and AI-assisted workflows routine, where they are awkward in a closed graphical program. The Usage Guide covers the input template, Colab Notebooks runs XSLOPE in a browser with nothing installed, and the API section documents every function.
Citing XSLOPE
If you use XSLOPE in published work, cite the paper:
Jones, N. L., & Williams, G. P. (2026). xslope: An open, validated Python package and desktop application for integrated seepage and slope stability analysis. SoftwareX, 36, 103018. https://doi.org/10.1016/j.softx.2026.103018
To cite the exact version you ran, add its archived release; every release has its own DOI, and the concept DOI 10.5281/zenodo.20709269 always resolves to the newest one.
Who makes it
XSLOPE is developed by Norman L. Jones, PhD, a professor in the Civil and Construction Engineering Department at Brigham Young University and founder and principal of Jones Geoscience LLC. Prof. Jones earned his PhD at the University of Texas under Stephen G. Wright, and has taught CE 544 — Seepage and Slope Stability Analysis at BYU for several decades. He can be reached at [email protected] or [email protected].
Feedback and bug reports
The best way to report a bug, suggest a feature, or ask whether XSLOPE can handle your problem is a GitHub issue. Go to github.com/njones61/xslope/issues, click New issue, and pick Bug report, Feature request or Question. In Studio, Help → Report a Problem… opens the bug report with your version and platform already entered. Each form asks for what is needed to act on it. For a bug, that is:
- what you did — the steps, or the analysis you ran;
- what you expected, and what happened instead, with any error message;
- your XSLOPE version — in Studio, About XSLOPE Studio in the XSLOPE
Studio menu on macOS or Help → About on Windows; in Python,
xslope.__version__— and whether you ran Studio on macOS or Windows or the Python package; - the input workbook, or a smaller one that shows the same problem, if you can share it.
Opening an issue needs a free GitHub account. Issues are public, so leave out anything confidential. If a model can't be shared, or you don't have a GitHub account, email instead.
Versions
XSLOPE follows semantic versioning. Workbooks from earlier versions open in the current one, and the Python API keeps its names within a major version. As with any slope stability software, check results independently before you rely on them in practice. Feedback is welcome — see Feedback and bug reports above.