Custom components

Streamlit custom components extend your app beyond built-in widgets with custom UI elements. V2 components offer better performance and multiple callbacks without iframes, while V1 components run in iframes with single callbacks.

V2 custom components

Backend (Python)

Register

Register a custom component.

Python
my_component = st.components.v2.component(
    html=HTML,
    js=JS
)
my_component()

Mount

Mount a custom component.

Python
my_component = st.components.v2.component(
    html=HTML,
    js=JS
)
my_component()

Frontend (TypeScript)

npm support code

Support code published through npm.

Terminal
npm i @streamlit/component-v2-lib

FrontendRenderer

Type alias for the component function.

TypeScript
import { FrontendRenderer } from "@streamlit/component-v2-lib";

FrontendRendererArgs

Type alias for the component arguments.

TypeScript
import { FrontendRendererArgs } from "@streamlit/component-v2-lib";

FrontendState

Type alias for the component state.

TypeScript
import { FrontendState } from "@streamlit/component-v2-lib";

CleanupFunction

Type alias for the component cleanup function.

TypeScript
import { CleanupFunction } from "@streamlit/component-v2-lib";

V1 custom components

Declare a component

Create and register a custom component.

Python
from st.components.v1 import declare_component
declare_component(
    "custom_slider",
    "/frontend",
)

HTML

Display an HTML string in an iframe.

Python
from st.components.v1 import html
html(
    "<p>Foo bar.</p>"
)

iframe

Load a remote URL in an iframe.

Python
from st.components.v1 import iframe
iframe(
    "docs.streamlit.io"
)
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