Clean diagrams
Orthogonal wires that route around blocks, branching and junctions, named nets, one-step undo, and Arrange to tidy a drawing.
Open-source multidomain simulation
Draw the system.
Simulate it.
Gradara is a graphical workbench for electrical, mechanical, thermal, and control models. Wire a diagram, set parameters, and run it with the OpenModelica solver on your own computer.
Free · Windows, macOS, Linux · Apache-2.0 · Early release
Multidomain
Real physics on every port.
217 built-in blocks, most of them wrapping the Modelica Standard Library. Physical connections follow conservation laws, so a circuit behaves like a circuit and a shaft carries torque. Signals and physics meet through explicit sensors and actuators.
Signal & control
Sources, math, continuous and discrete blocks, nonlinearities, PI and PID, Clarke and Park transforms, and signal buses.
causal · realLogic
Boolean gates, comparators, hysteresis, flip-flops, edges, and timers for switching and protection logic.
causal · true/falseElectrical
Sources, passives, op-amps, diodes, thyristors and transistors, bridges, buck and boost converters, PWM, transformers, and DC, induction, and synchronous machines.
v · i3-phase
Three-phase sources, R, L, and C loads, star and delta connections, a Dy transformer, inverters, and power sensors.
v · i per phaseRotational
Inertias, springs, dampers, gears, loads, and speed and torque sensors coupled to machines.
φ · τTranslational
Masses, springs, dampers, forces, and position sensors, down to a vehicle on a road.
s · fThermal
Heat capacitors, conduction, convection, and heat sources for losses and cooling.
T · Q̇Magnetic
Reluctances, windings, and magnetomotive sources for inductors and transformer cores.
V_m · ΦThe workbench
Built for engineers
who draw first.
Direct manipulation stays fast, and the numerical work goes to a proven Modelica compiler and solver. Your models are plain files on your computer.
OpenModelica inside
Models compile to Modelica and run with the built-in OpenModelica 1.27 and the Modelica Standard Library 4.1.0, including events and stiff systems.
Results inspector
Plot any logged net or output, zoom into switching ripple, keep event pairs, and download the full CSV.
Subsystems and variants
Group blocks into subsystems with typed ports, keep alternative designs behind one block, and switch whole configurations in one click. Worked examples from a DC motor to a three-level EV drivetrain.
Inspect and export
Read and edit block equations, export Modelica source, and generate compile-checked C11 for a controller: a subsystem, selected signal blocks, or the one Gradara detects.
Local and private
Everything runs on your computer. No account needed to model or simulate, and no analytics or tracking.
Optional AI
Describe the missing part.
Get a checked block.
When the library does not have what you need, describe it. Gradara writes the equations, checks them with the compiler, and places a block you can inspect and edit. It can also build a complete first model from a description, propose checked edits to the model you have open, and explain why a run failed. Nothing changes until you review and apply it.
Describe
Choose signal, electrical, mechanical, thermal, or multidomain, and say what it should do.
Generate
The AI returns a structured definition with real ports and parameters, never free-form code.
Check
Schema validation and the OpenModelica compiler run before anything reaches your diagram. One automatic repair if needed.
Own it
The block is saved in your model and your local library. Reuse and simulate it without calling AI again.
› A thermal model of a MOSFET on a heatsink with junction, case, and ambient nodes
generating definition · 3 heat ports · 4 parameters
compiler check passed · placed as MOSFET thermal
generating definition · 3 heat ports · 4 parameters
compiler check passed · placed as MOSFET thermal
Illustrative request. Results depend on the description and the chosen block type.
Pricing
The workbench is free.
AI is pay as you go.
Buy prepaid credits inside the app when you need them, or use your own AI account. No subscription and no card on file.
Gradara
Free
The complete workbench, forever.
- Modeling, simulation, and results
- All examples and export formats
- Your own OpenAI or Anthropic key, billed by them
- Open source under Apache-2.0
Gradara AI · Starter
$10 100 credits
Sign in and go. No keys or setup.
- 20 free credits when you sign up
- Repair attempts included
- Not charged if a request fails before producing output
- Credits never expire while your account is active
Gradara AI · Pro
$50 550 credits
For regular use across projects.
- 10% more credits per dollar
- Same checks and privacy
- Receipts by email from Stripe
- Buy from Settings in the app
2credits per generated block
20credits per complete model build
2credits per C template written for a custom block
4credits per assistant edit, +2 per new or rewritten block
2credits to explain a problem; a fix adds the edit
Drawing, simulating, and exporting Modelica or C code for library blocks never use credits or an account. Only the AI features above do, and the app shows the price before you send.
Privacy
Your models stay
on your computer.
Gradara is local first. Nothing leaves your computer unless you ask for an AI feature. Read the privacy notice.
No content retention
Gradara AI processes requests in memory and does not store or log prompts, models, equations, or responses. Our AI provider, Anthropic, may keep requests briefly for abuse monitoring.
Minimal records
Only your email, credit balance, purchases, and per-request usage (task, model, token counts, time), with usage records deleted after about 13 months.
Keys in your keychain
Your own API keys and your sign-in live in the operating system keychain and go only to their provider.
Delete any time
Delete your Gradara AI account from Settings. Your local models are never affected.
Download
Install in minutes.
One download. The simulation engine, OpenModelica with the Modelica Standard Library, is included: nothing else to install.
Windows
Windows 10 or 11, 64-bit. Install and run your first model; the engine is built in.
Installer · x64macOS
Apple silicon or Intel, macOS 13 or newer. The engine runs in a small virtual machine built into the app. No Docker needed.
Disk image · .dmgLinux
64-bit Linux, .deb or AppImage. The engine is built in and compiles with your system's gcc.
AppImage · Debian and UbuntuStep-by-step instructions for each system are in the install guide. Prefer to build it yourself? Clone the repository and follow the setup guide. Release notes are on GitHub Releases.
FAQ
Questions.
Is Gradara really free?
Yes. The app is open source under Apache-2.0 and every modeling and simulation feature is free. Only the optional hosted AI uses paid credits, and you can use your own AI account instead.
Do I need Docker or OpenModelica?
No. Every installer includes the simulation engine. On macOS, where OpenModelica publishes no native builds, Gradara runs it in a small virtual machine that ships inside the app and uses Apple's built-in Virtualization framework. The virtual machine has no network access and only sees Gradara's data folder.
How do I know the results are right?
The physics comes from OpenModelica and the Modelica Standard Library. Automated tests compare Gradara's results with closed-form answers, from an RC circuit's time constant to a buck converter's ripple; the validation page lists them with measured values. Gradara is not certified for safety-critical use.
Can it open Simulink models?
No. Gradara is an independent tool with its own model format and exports standard Modelica source. MATLAB and Simulink files are not supported.
Does my model leave my computer?
Only when you use an AI feature, and only the context that request needs. Gradara AI does not store it; Anthropic, which runs the model, may keep it briefly for abuse monitoring. Simulation always runs locally.
Can I trust AI-generated blocks?
Every block passes schema checks and the OpenModelica compiler before it appears, and its equations are visible and editable. Compiling is not the same as being physically correct, so review blocks the way you would review any model.
Who makes Gradara?
Gradara is developed by Virtu Services LLC, with contributions from the open-source community.
Start with an example.
Simulate in minutes.
Open the DC motor or the buck converter, press Run, and explore the results.