Streamlit Frontend is a set of frontend packages tied to behaviors that make up a Streamlit App. Originally, Streamlit Frontend was a monolith, but we have since found unique ways to inject Streamlit behavior in multiple different products.

The following are packages:

• app - The Streamlit app layout (used to bundle into Streamlit library)
• component-v2-lib - Support library for Streamlit Components v2.
• connection - Code to establish the Websocket connection
• eslint-plugin-streamlit-custom - ESLint plugin with custom rules.
• lib - Right now, this is a catchall, but this is being refactored to be more focused. Namely, it supports a Streamlit "View" that contains elements, widgets, and layouts.
• protobuf - Our protobuf code in one library.
• typescript-config - configuration for typescript across all the packages.
• utils - some shared utils used across Streamlit

• Run yarn start or make frontend-dev to start the development server.

The dependency diagram below describes the interaction between the packages in our workspace.

graph LR;
  app -->|side loads| lib
  app -->|depends on| connection
  app -->|depends on| protobuf
  app -->|depends on| utils

  lib -->|depends on| protobuf
  lib -->|depends on| utils

  connection -->|depends on| protobuf
  connection -->|depends on| utils

  lib -.->|dev dep| typescript-config
  connection -.->|dev dep| typescript-config
  protobuf -.->|dev dep| typescript-config
  utils -.->|dev dep| typescript-config
  app -.->|dev dep| typescript-config

Streamlit is completely free and open-source and licensed under the Apache 2.0 license.