Stabileo

Structural analysis, in a browser tab.
A free and open structural-analysis platform. The solver is a Rust engine compiled to WebAssembly and it runs on your machine — no install, no licence key, no account.

Open the editor · Blog · What works today · Why it exists · Features · Getting started · Docs

_{3D industrial warehouse with Pratt roof trusses and crane bridge. Orange overlay shows the deformed shape under load. 216 nodes, 538 elements, 30 supports.}

_{Same structure with stress utilization color map (σ/fy). Blue = lightly loaded, yellow = moderate, red = approaching yield.}

Stabileo ships three modes, and they are not equally finished. This is the same status the site itself states, in the same words, because a README that promises more than the product delivers costs more trust than the extra features would have bought.

The solver capabilities listed further down are engine-level. The engine implements more than any one mode currently exposes, which is exactly why the modes are labelled the way they are here.

The interface is available in English, Spanish and Portuguese.

The dominant structural analysis tools — SAP2000, ETABS, Robot, RFEM — cost thousands of dollars per year, run on Windows, require installation and licence servers, and are closed source. Open-source solvers like OpenSees are powerful but require scripting and have no visual interface.

Stabileo is different:

• Browser-native. Open stabileo.com and start. No download, no licence key, no account.
• Real solver. A Rust engine compiled to WebAssembly, running on your own machine — your models never leave it.
• Real-time. The solver runs on every edit. Move a node, change a load, resize a section, and the results follow.
• It shows the development, not only the answer. Kinematic analysis, section analysis and the step-by-step Direct Stiffness wizard explain why a result is what it is — including when the formula you were taught does not apply. See the note on that.
• Structured model surface. The browser UI, the APIs and the AI workflows all target the same model/snapshot contract instead of hidden prompt magic.
• AI-ready, but deterministic. AI can generate, edit, review and explain models; the solver stays the source of truth for the mechanics.
• Open source. Read the solver, trace the maths, send improvements.

Tech stack: Svelte 5 front end, Rust solver engine via WASM, Three.js for 3D.

Originally built for structural engineering courses at FIUBA (University of Buenos Aires).

Stabileo's strongest technical wedge is not "AI chat" by itself. It is a structured structural model and a deterministic solver that humans and AI can both operate.

• Engineers model directly in the browser and inspect diagrams, stresses, reactions and diagnostics.
• AI workflows build or edit the same structured model snapshot, then hand it to the same solver for real analysis.
• Review and explanation tools sit on top of solver artefacts and diagnostics instead of inventing mechanics.

Start here:

• Docs hub
• Quick start
• AI modeling workflow
• Solver reference

• 2D and 3D linear static, second-order, buckling, modal, response spectrum, time history, harmonic response, and moving loads
• Corotational and material nonlinear analysis, plastic analysis, fiber beam-column elements
• Staged construction, prestress/post-tension, cable analysis, contact/gap behavior, nonlinear SSI
• Initial imperfections, residual stress, creep/shrinkage
• Multi-family shell stack: MITC4 (ANS + EAS-7), MITC9, SHB8-ANS solid-shell, curved shells
• Guyan and Craig-Bampton model reduction
• Sparse-first assembly and solve with AMD ordering, 22-234× speedups on shell models
• Load combinations, envelopes, section analysis, stress recovery, kinematic diagnostics

Benchmarked against NAFEMS, ANSYS Verification Manual, Code_Aster, SAP2000, OpenSees, Robot, STAAD.Pro, and textbook solutions. See BENCHMARKS.md for full coverage.

stabileo.com/blog — longer pieces on how the solver works, what the code checks actually verify, and the decisions behind them, in English, Spanish and Portuguese. Every figure in them is produced by the engine before the prose is written, and several posts embed the real editor on the model they describe.

• The determinism boundary — why an AI agent must not do the arithmetic
• What free software computes, and what it never explains — where the free tools stop
• Flexural verification to CIRSOC 201 — the steps that decide the outcome
• Bredt or Saint-Venant — which torsion theory applies, and what picking wrong costs

Use it now. Open stabileo.com. Works in any modern browser.

Run locally:

git clone https://github.com/lambdaclass/stabileo.git
cd stabileo/web
npm install
npm run dev       # http://localhost:4000

npm test           # run the web test suite
npm run build:only # production build -> web/dist/

Requires Node.js >= 18.

npm run build does the same build and then prerenders every public route, which it does by driving the real page in headless Chromium — so it needs a browser installed first:

npx playwright install chromium
npm run build     # build + prerender, what CI and the deploy run

Nothing else in the workflow needs it: npm run dev, npm test and build:only do not prerender.

Pull requests are welcome. For major changes, open an issue first to discuss the approach.

To report a vulnerability, email security@lambdaclass.com.

AGPL-3.0

• Bautista Chesta — Civil Engineer (FIUBA), UX/UI and project management
• Diego Kingston — Ph.D. in Engineering (UBA), product–solver integration
• Federico Carrone — Founder of Lambda Class, solver lead

With contributions from mathematicians, physicists, computer engineers, and computer scientists at Lambda Class.