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Flowcharts, runnable in your browser!


  • simple and fast flowchart editor
  • run program inside your browser, locally
  • export program into JSON
  • readonly mode for documentation/tutorials
  • predefined functions
  • precise error reporting

Data types

  • Integer for whole numbers
  • Real for decimal numbers
  • String for text
  • Boolean for true/false


  • +, -, *, /, % for arithmetic operations
  • &&, ||, ! for boolean operations
  • <, <=, ==, !=, >, >= for comparing values

The rules of precedence should be familiar to you from mathematics.
For example:

  • * has higher precedence than +:
    2 + 2 * 2 == 2 + 4 == 6.
  • && has higher precedence than ||:
    true || false && true == true || false == true.


You can define new functions and use them from your main function.
Functions have a return type, the type of value which it returns.
For example, if you calculate a sum of two Integers, the result would also be an Integer (return type).

The return type can also be Void, which means it doesn't return anything, it just executes and that's it.
For example, it could calculate something, print it and exit.

There are also some predefined functions that you can use, they are defined automatically in FlowRun.
You can find them here

Implementation details

Written in ScalaJS.
Uses d3-graphviz to display the flowcharts.