Theming

This section provides examples of how Streamlit page elements are affected by the various theme config options.

• primaryColor
• backgroundcolor
• secondarybackgroundcolor
• textcolor
• font
• base

Streamlit configuration

When you install Streamlit, a command-line (CLI) tool gets installed as well. The purpose of this tool is to run Streamlit apps, change Streamlit configuration options, and help you diagnose and fix issues.

• What is the command-line interface (CLI)?
• How to run Streamlit apps from the CLI?
• View documentation from the CLI
• Clear cache from the CLI
• How to set configuration options?
• View all configuration options

Optimize performance with st.cache

Streamlit provides a caching mechanism that allows your app to stay performant even when loading data from the web, manipulating large datasets, or performing expensive computations. This is done with the @st.cache decorator.

• What is st.cache?
• Basic usage
• Caching when the function arguments change?
• Caching when the function body changes
• Caching when an inner function changes
• Use caching to speed up your app across users
• How to mutate cached values?
• Advanced caching

Experimental cache primitives

Streamlit provides two experimental primitives to memoize function executions and store singleton objects.

@st.experimental_memo is used to store expensive computation which can be "cached" or "memoized" in the traditional sense.

@st.experimental_singleton is a key-value store that's shared across all sessions of a Streamlit app. It's great for storing heavyweight singleton objects across sessions (like TensorFlow/Torch/Keras sessions and/or database connections).

• Problems with st.cache
• @st.experimental_memo
• Properties of @st.experimental_memo
• @st.experimental_singleton
• How @st.experimental_singleton compares to @st.cache
• Which to use: memo or singleton?

Add statefulness to apps

Session State is a way to share variables between reruns, for each user session. In addition to the ability to store and persist state, Streamlit also exposes the ability to manipulate state using Callbacks.

• What is Session State?
• How to initialize Session State items?
• How to read and update Session State items?
• How to use callbacks in Session State?
• How to use args and kwargs in callbacks?
• How to use callbacks in forms?
• How is Session State related to Widget State?
• Caveats and limitations

Pre-release features

At Streamlit, we like to move quick while keeping things stable. In our latest effort to move even faster without sacrificing stability, we're offering our bold and fearless users two ways to try out Streamlit's bleeding-edge features.

• Nightly releases
• Beta and experimental features

Advanced notes on widget behavior

Widgets are magical and often work how you want. But they can have surprising behavior in some situations. This section provides is a high-level, abstract description of widget behavior, including some common edge-cases.