Develop Data Apps

Build and preview Shiny, Streamlit, Dash, FastAPI, and Flask apps in Positron. Launch with one click of the Play button, or use our debugging support.

Positron provides a simplified method for running interactive data apps via the Play button. Instead of running an app from a Terminal, you can run supported apps by selecting the Play button in Editor Actions. Additionally, you can start a supported app in debug mode through the Play button context menu.

Editor action bar with the Play button highlighted in a red box, showing a Python Streamlit file open in the Editor.

Positron App Launcher button in Editor Actions

Supported app frameworks

Currently, Positron supports the following Python app frameworks:

Running a data app

  1. Open the .py file of a supported app framework.

  2. In Editor Actions, select Play.

    Close-up of the Play button in the Editor action bar.

    Positron App Launcher Play button

Then, Positron runs the app in a dedicated Terminal tab and opens the app URL in the Viewer pane. If your application does not automatically open in the Viewer, check that the settings python.terminal.shellIntegration.enabled and terminal.integrated.shellIntegration.enabled are enabled.

Streamlit app running in the Positron Viewer pane showing a slider input and squared value output.

A Streamlit app in the Positron Viewer

To stop the app, you can either:

  • Select the interrupt button in the Viewer pane toolbar.
  • Select the Terminal tab running the application and use the trash can icon to delete the Terminal or press to stop the process.

Debugging a data app

  1. Open the .py file of a supported app framework.

  2. Set breakpoints in the .py file by selecting the editor margin.

    Editor showing a red breakpoint dot in the left margin next to a line of Python code.

    Editor margin area for adding breakpoints

  3. Select the Play button dropdown context menu and choose Debug [{SUPPORTED_APP_TYPE}] App in Terminal.

    • For this example, we select Debug Steamlit App in Terminal.

    Play button dropdown menu showing options including Run Streamlit App in Terminal and Debug Streamlit App in Terminal.

    Play button dropdown context menu

Then, Positron runs the app in a dedicated Terminal tab, opens the app URL in the Viewer pane, and starts the app in debug mode.

Positron IDE showing a Streamlit app paused at a breakpoint with the debug toolbar visible and Variables displayed in the Debug pane.

A Streamlit app running in debug mode; paused at a breakpoint