This tool is under development and currently in beta testing. We would love to hear from you! Let us know your feedback at hello@joshsim.org and we are here to help if you run into any issues.

Josh Simulation Editor

This web-based editor allows for rapid prototyping Josh agent-based simulations from your browser. These scripts are only saved within your browser and are not sent to external servers unless requested. Try out small scripts in your browser. Then, run on cloud or CLI when ready to execute larger simulations.
New File Load File Save File

Open File

Note that this will override code currently entered into the application.

Open Cancel
Loading indicator Loading please wait...

Simulation

Run

This will run your simulation in your browser using your computer.

Comma-separated list of time steps to export. Leave empty to export all steps.
Engine

The location where this should run. Some options may be faster than others but require more set up. Want to try the free non-profit Josh Cloud? Email us.

Your local application was not found. See local Josh application instructions.
Local application found!
Run Cancel

Data Files

These files can be sent along with your simulation. We recommend jshd and jshc for geospatial data and configuration parameters respectively. Larger data files may be sent by using Josh outside of the browser.

MB out of MB used
Add File Done
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Config

Variables defined here are accessible from config editor.testVariable. This file can be edited to configure simulation parameters without modifying Josh code.

Save Cancel

AI Assistant

For privacy reasons, you can use any Large Language Model (LLM) of your choice to assist with creating Josh simulations. Josh implements the llms.txt protocol to provide standardized documentation for AI assistants. To help the AI understand Josh, please direct it to read the following documentation:

For complete language reference:
For quick navigation and tutorials:

Copy and paste these URLs into your conversation with any AI assistant (ChatGPT, Claude, etc.) and ask it to read the documentation. Then you can ask for help creating Josh simulations, debugging code, or understanding language features.

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Run

Execution status

⌛ ✅ Please wait...
⚠️ Encountered error: .
⏰ Ran in minutes and seconds.
💾 Collected records.
🚀 Need to go faster? Run on cloud or CLI.

Results

No data were reported for this simulation. To add data to an export, consider adding code like this: 
start patch Default

  # ...

  export.averageAge.step = mean(ForeverTree.age)
  export.averageHeight.step = mean(ForeverTree.height)

  # ...

end patch
Then, specify that the results should be written to this editor's visualizations: 
start simulation Simulation

  # ...

  exportFiles.patch = "memory://editor/patches"

  # ...

end simulation

Results

Download Results

This will generate a download to continue analysis of simulation results oustide of this web editor.

Download Close

Map Settings

You may optionally add a map baselayer like satellite imagery to your visualization using Mapbox, a service that is not affiliated with the Josh project. This requires getting a Mapbox key and will send the boundaries of your simulation to mapbox in order to request imagery. Communication will go directly to Mapbox and not through Josh servers. Requests will only be made if the basemap is not none.

Please specify latitude and longitude in your simulation in order to add a map layer.
OK
Showing that of to .
Configure Map