A process simulator that runs in your browser: steady-state, pressure-driven and dynamic flowsheets, rigorous thermodynamics, and an AI copilot that builds and explains them. There is nothing to install.

Does the AI calculate the results?

No. The copilot proposes a flowsheet or a change and explains it; the deterministic solver computes every temperature, duty and composition you see. A flowsheet from the copilot that does not validate is not applied.

Will it feel familiar if I have used Aspen Plus or HYSYS?

That is the intent. The workbench has a ribbon, an All Items tree, a form for each block and the three run modes — steady state, pressure driven and dynamics — so the habits carry over.

Can it open my Aspen or HYSYS cases?

Aspen Plus .bkp and .apw, HYSYS .hsc and DWSIM files import with deterministic parsing and a report of what was recovered. A HYSYS .hsc import is partial — unit names and types, not connectivity — and the report says so.

Which thermodynamic models are included?

Peng-Robinson and SRK (including Gᴱ mixing rules), NRTL, UNIQUAC, UNIFAC, PC-SAFT, CPA, GERG-2008, electrolyte NRTL, Pitzer and the IAPWS steam tables — more than 30 property packages in all.

Yes. The Python SDK (pip install flowsim-sdk) creates, runs and reads simulations, and its results are the same objects the canvas shows.

How much does it cost?

It is free to start, with no credit card. Paid plans add higher limits and team features; the pricing page has the details.

A process simulator that runs in your browser: steady-state, pressure-driven and dynamic flowsheets, rigorous thermodynamics, and an AI copilot that builds and explains them. There is nothing to install.

Does the AI calculate the results?

No. The copilot proposes a flowsheet or a change and explains it; the deterministic solver computes every temperature, duty and composition you see. A flowsheet from the copilot that does not validate is not applied.

Will it feel familiar if I have used Aspen Plus or HYSYS?

That is the intent. The workbench has a ribbon, an All Items tree, a form for each block and the three run modes — steady state, pressure driven and dynamics — so the habits carry over.

Can it open my Aspen or HYSYS cases?

Aspen Plus .bkp and .apw, HYSYS .hsc and DWSIM files import with deterministic parsing and a report of what was recovered. A HYSYS .hsc import is partial — unit names and types, not connectivity — and the report says so.

Which thermodynamic models are included?

Peng-Robinson and SRK (including Gᴱ mixing rules), NRTL, UNIQUAC, UNIFAC, PC-SAFT, CPA, GERG-2008, electrolyte NRTL, Pitzer and the IAPWS steam tables — more than 30 property packages in all.

Yes. The Python SDK (pip install flowsim-sdk) creates, runs and reads simulations, and its results are the same objects the canvas shows.

How much does it cost?

It is free to start, with no credit card. Paid plans add higher limits and team features; the pricing page has the details.

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Launch Free Simulator

Simulation gallery

Kinetic CSTR

KineticsArrheniusCSTR

See it live

Open this exact flowsheet in the workspace, already solved — tweak a spec and re-run.

Launch interactive model

A continuous stirred-tank reactor with an Arrhenius first-order rate — outlet conversion comes from the kinetics, not a specified value. The chemistry is the acid-catalysed etherification of ethanol, 2 C2H5OH -> (C2H5)2O + H2O. (It used to be written as ethanol -> water, which balances no atom but oxygen.)

The flowsheet

The solved topology — every unit op's real duty, conversion, or split, read straight off a genuine converged solve.

FEED

CSTR

OUT

The stream table

Every stream's flow, temperature, pressure, and composition — real converged numbers, not placeholders.

See it live

Open this exact flowsheet in the workspace, already solved — tweak a spec and re-run.

Launch interactive model

Stop fighting legacy software. Build your first flowsheet in 60 seconds.

Start free See the 60-second demo