Every equation, every Newton iteration, every K-value — visible, in the source and as it runs. Free and open. And it runs in your browser, with nothing to install.
Open code · Visible equations · Cleaner industry.
Created by Vítor Geraldes — chemical engineer, process-modelling researcher, and open-source builder.
A student opens the big commercial simulator, picks a thermodynamic method from a list, clicks Run, and gets a number. Which equation? Which assumption? Why that K-value? Hidden. You are taught to trust the box.
A method is a name in a dropdown. The maths is sealed. When the answer is wrong you cannot see where — only that it differs from the lab.
The model is open in the source and it narrates itself as it solves. You choose a model because you saw it fit the data — not because a badge said "recommended".
A flash converging, live. The same output in the source, the terminal, and the browser — there is no hidden layer.
// Isothermal flash · benzene/toluene · 370 K, 1 bar · Raoult iter residual T(K) V/F 0 1.84e-01 370.00 0.500 1 2.07e-02 370.00 0.486 <- Newton on the tear 2 3.1e-04 370.00 0.4912 3 5.6e-08 370.00 0.49118 converged K_benzene = 1.71 K_toluene = 0.68 (Psat/P, you can read it)
A real simulator — steady-state, dynamic, batch — and a property bench that lets you build and trust the thermodynamics before you wire a flowsheet.
Flash, distillation, reactors (CSTR/PFR/Gibbs), heat exchange, rotating equipment, recycle with Newton-on-tears. Four solvers, one per problem class.
Navigate any component or mixture and plot its properties interactively — vapour pressure, density, compressibility — and see the curves before you commit. Runs in the browser; nothing to install.
Create a component from its groups, overlay models on your measured data, test the data's consistency, fit parameters — then carry a curated file into the run.
A spiral-wound module with solution-diffusion + film model — the research edge a general simulator does not reach.
Plain-text dictionaries on disk are the source of truth. Edit them in any editor — increasingly with an AI agent at your side.
Sweep a parameter, minimise a cost, fit to data — the outer-driver layer wraps every run.
Guthrie module costs, utility allocation by temperature level — the report a project actually needs.
No download. No install. No licence. Open a page, pick a tutorial, watch it solve. Works on any laptop, even a Chromebook.
▶ Launch the simulatorWant to author your own case? Download it and point your own assistant at it on your PC — the dicts are just files.
Choupo is open-source and funded by adoption, papers, and standing — not licence fees. A student can read it, a researcher can extend it, and anyone can run it for free — to design better, cleaner, more efficient processes.
Democratizing process simulation is not a convenience — it is infrastructure for a cleaner industry.
If you cannot see the equation, you are not learning the process — you are trusting the box. Choupo has no box.
Contribute models, tutorials, tests, documentation, validation data, or new unit operations. Choupo is made for students, researchers, and engineers who want process simulation to be open, inspectable, and useful.
Public source, contribution guide, and a community forum — coming soon.
CHOUPO was created by Vítor Geraldes, a chemical engineer and process-modelling researcher.
Vítor Geraldes is also an Associate Professor of Chemical Engineering at Instituto Superior Técnico, University of Lisbon. This affiliation is provided for identification only. CHOUPO is an independent open-source project and is not an official product of Instituto Superior Técnico or Universidade de Lisboa.