FeenoX

FeenoX is a scriptable computational-engineering solver for advanced users who define analyses in text and work in Unix-style environments. It is strongest for engineers, academics, and automation-heavy teams that need open, repeatable calculations rather than a visual modeling desktop.

Overview

FeenoX addresses mathematical problems, ordinary and differential-algebraic equations, and finite-element partial differential equations. Its application range includes heat conduction, thermo-mechanical analysis, modal analysis, neutron diffusion, and neutron transport. Problems live in self-descriptive, English-like plain-text input files, so changing an analysis does not require recompiling. That favors version-controlled, reproducible workflows, while requiring users to understand and maintain the input syntax themselves.

The software is free in both price and freedom, released under the GNU General Public License version 3 or later. Source code and dependencies are open, and unit, regression, mathematical, and code-verification tests are provided. The license permits modification and redistribution under its terms, with no warranty to the extent permitted by law.

Key features

Meshes, solvers, and output

Input meshes use Gmsh's .msh format. Results can be written as Gmsh MSH files or ParaView VTK and VTU files, giving established routes into mesh and visualization pipelines. GNU GSL, SUNDIALS, PETSc, and SLEPc supply the computational foundations. This is a practical fit for teams already using those ecosystems; it is less accommodating to workflows built around proprietary formats or visual model setup.

Parallel and connected workflows

MPI parallelization allows a problem to run across multiple computers, and the design targets arbitrarily scalable remote servers. FeenoX can sit behind web interfaces, REST APIs, standard post-processing tools, Markdown, LaTeX reporting, or large-language-model integrations. SunCAE provides web access, while CAEplex offers a browser-based cloud interface. Those options make the solver useful as a backend, although the core product remains command-line and text driven.

Open development

Users can seek help in GitHub Discussions and report bugs through GitHub Issues. Contributions from hackers and academics are welcomed, particularly new PDEs and formulations. That model suits organizations able to read source and participate upstream more than teams expecting a commercial support desk.

Pricing

The FeenoX plan costs free. It is GNU GPLv3+ open-source software with no graphical interface, targets GNU/Linux, and generic binaries omit MUMPS and MPI. The separate Free plan is also free; no paid pricing is stated. There are no seat charges, quotas, or renewal terms published. Choose it when license freedom and source access matter; the trade-off is that installation, workflow construction, and any needed support remain your responsibility.

Platforms

FeenoX is delivered as a desktop-oriented tool with API, Linux, self-hosted, and web availability. Official installation routes include Debian or Ubuntu packages, statically linked GNU/Linux binaries, source tarballs, and the GitHub repository. Ubuntu support starts at version 25.04. Generic static binaries run as standalone GNU/Linux executables, but they do not support MUMPS or MPI and use only basic optimization flags, so users needing those capabilities should use a suitable package or build from source.

There is no graphical interface, and the project is not expected to run in Windows; official documentation targets GNU/Linux. Offline access and data export are supported, while 3D visuals are available through the output and visualization workflow rather than a built-in GUI.

Who it's for

FeenoX is aimed at industry engineers, Unix hackers, academic professors, and other advanced users. It fits repeatable simulation pipelines, remote or parallel computation, and organizations that want to inspect, modify, and redistribute their solver. It is a poor match for beginners seeking point-and-click finite-element setup, Windows-first teams, or anyone who needs integrated assessment tools or a lesson library.

Pros and cons

• Pros: broad coverage from ODE/DAE systems to thermal, mechanical, modal, and neutron analyses; plain-text inputs make revisions and automation reproducible; MPI supports multi-computer execution; open licensing, source, dependencies, and verification tests support audit and customization; Gmsh and ParaView formats connect to established toolchains.
• Cons: no graphical interface places the burden of modeling on text files; Windows is outside the expected platform; generic binaries lose MUMPS and MPI support and use basic optimization; no warranty and community-based support may not satisfy teams requiring contracted assistance.

Alternatives

For broader operating-system coverage and a free GPL-based CFD platform with separate support and customization services, consider OpenFOAM. OpenSim is a free, open-source option spanning Linux, macOS, and Windows, though downloading requires a SimTK account. For command-line or file-based circuit simulation without schematic entry, choose ngspice. Xcos is a free option distributed with Scilab across Linux, macOS, and Windows.

SimFlow offers a freemium, trial-enabled path with Linux, macOS, Windows, and web availability. GNU FisicaLab is free GPL software for Linux and Windows, while Step is a free GPL-2.0+ choice for Linux. ASCEND is another free, open-source physics-simulation alternative across Linux, macOS, and Windows. Browse Physics Simulation Software for the wider category.

Verdict

Choose FeenoX if you are an advanced engineer or researcher who values open source, text-defined models, automation, and scalable GNU/Linux computation. Its strongest reason to choose it is the combination of broad engineering problem coverage and an API-friendly, reproducible workflow at no cost. Look elsewhere if you need a graphical interface, Windows support, or generic binaries with full MUMPS and MPI capabilities.