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Streamlit — script-style dashboards

Version: 1.50.x
Type: Pure Python
SPM target: Streamlit
Auto-includes: Tornado, Click, Watchdog, Typing_extensions, PyArrow
Total Python modules: 213

Re-runs your whole script top-to-bottom on every widget interaction. State persists automatically (widgets keep their values; @st.cache_data caches function results). Best fit for data-exploration UIs where you want to write Python, not callbacks.

Modules

Top-level entry points

Module What it does
streamlit.__init__ The big public API surface — every st.something is re-exported here. Categories below.
streamlit.__main__ python -m streamlit run script.py entry
streamlit.config / config_option / config_util Config loading (env vars, .streamlit/config.toml, programmatic)
streamlit.version Version string
streamlit.errors / error_util / exception_util Error types + handlers
streamlit.logger Logging setup

Top-level st.* API (curated)

Category Functions
Text st.write, st.markdown, st.title, st.header, st.subheader, st.caption, st.code, st.text, st.latex, st.divider
Data display st.dataframe, st.table, st.metric, st.data_editor, st.json
Charts st.line_chart, st.area_chart, st.bar_chart, st.scatter_chart, st.map, st.pyplot, st.altair_chart, st.vega_lite_chart, st.plotly_chart, st.bokeh_chart, st.pydeck_chart, st.graphviz_chart
Inputs st.button, st.download_button, st.checkbox, st.toggle, st.radio, st.selectbox, st.multiselect, st.slider, st.select_slider, st.text_input, st.number_input, st.text_area, st.date_input, st.time_input, st.color_picker, st.file_uploader, st.camera_input
Media st.image, st.audio, st.video, st.pdf
Layout st.columns, st.tabs, st.expander, st.container, st.sidebar, st.empty, st.popover, st.form, st.form_submit_button
State / cache st.session_state, st.cache_data, st.cache_resource, st.rerun, st.stop
Progress / status st.progress, st.spinner, st.status, st.toast, st.balloons, st.snow
Alerts st.success, st.info, st.warning, st.error, st.exception
Multi-page st.navigation, st.Page, st.switch_page
Misc st.write_stream, st.fragment, st.context, st.help, st.echo

streamlit.elements — widget implementations

Submodule Provides
elements.alert success / info / warning / error
elements.arrow Apache Arrow-based dataframe serialization
elements.balloons, elements.snow Celebration animations
elements.bokeh_chart Bokeh chart renderer
elements.code, elements.heading, elements.markdown, elements.html, elements.json, elements.text Text-display elements
elements.dialog_decorator @st.dialog
elements.doc_string, elements.exception, elements.empty Helper elements
elements.form st.form / st.form_submit_button
elements.graphviz_chart Graphviz renderer
elements.iframe, elements.image, elements.media, elements.pdf Embeds
elements.layouts columns, tabs, expander, container, sidebar, popover
elements.map, elements.deck_gl_json_chart Map / 3D-map renderers
elements.metric st.metric
elements.plotly_chart, elements.altair_chart, elements.vega_lite_chart, elements.line_chart, elements.area_chart, elements.bar_chart, elements.scatter_chart, elements.pyplot Chart renderers
elements.progress, elements.spinner, elements.toast Feedback
elements.widgets/ The actual input-widget implementations (button, checkbox, radio, …)
elements.write_stream Async chunk streaming

streamlit.runtime — server runtime

Submodule Provides
runtime.app_session Per-session state + script-runner orchestration
runtime.caching cache_data / cache_resource backends, hashing, storage
runtime.fragment @st.fragment partial re-renders
runtime.legacy_caching Older @st.cache (kept for compat)
runtime.memory_session_storage, runtime.memory_uploaded_file_manager, runtime.memory_media_file_storage In-memory storage backends
runtime.runtime The Runtime orchestrator
runtime.scriptrunner/ Compiles + executes user scripts on every run
runtime.secrets st.secrets (Tomli-backed secrets.toml loader)
runtime.state/ st.session_state machinery
runtime.stats Internal metrics
runtime.uploaded_file_manager st.file_uploader server side
runtime.websocket_session_manager Tornado WebSocket plumbing

streamlit.web — HTTP / WebSocket server

Submodule Provides
web.bootstrap bootstrap.run(script, …) — programmatic launch entry. iOS-patched: signal-handler skip on non-main thread + preview-signal + clean-shutdown hooks
web.cli The streamlit CLI (streamlit run …, streamlit hello, …)
web.server/ Tornado handlers: WebSocket, static assets, health, media, components
web.cache_storage_manager_config Cache backend selection

streamlit.commands — top-level shorthand commands

Submodule Provides
commands.page_config st.set_page_config(...)
commands.execution_control st.rerun, st.stop
commands.experimental_query_params URL query params API
commands.navigation st.navigation, st.Page, st.switch_page

streamlit.components

Submodule Provides
components.v1.components Iframe-based custom components
components.v1.custom_component declare_component (third-party React component loader)

streamlit.connections — data-source helpers

Submodule Provides
connections.base_connection Base class for st.connection
connections.snowflake_connection, connections.sql_connection, connections.snowpark_connection Built-in connectors

streamlit.proto, streamlit.vendor, streamlit.external

proto — protobuf message types for the wire protocol.
vendor — copies of small third-party utilities streamlit depends on.
external — third-party adapters.

Other utilities

Module What it does
streamlit.dataframe_util DataFrame coercion (pandas, polars, pyarrow, numpy)
streamlit.delta_generator Core widget-tree builder
streamlit.column_config Column-config types for st.dataframe
streamlit.cursor Element-tree cursor
streamlit.user_info, streamlit.auth_util User identity helpers
streamlit.material_icon_names All Material Symbols icon names

streamlit.watcher

File-watching for auto-rerun on save. Flaky in the iOS sandbox — set server.runOnSave=False and use the rerun button instead.

streamlit.hello

Built-in demo app (streamlit hello).

iOS-specific patches

See web-stack.md § Streamlit for details.

Patch file Why
streamlit/web/bootstrap.py _set_up_signal_handler signal.signal works only on main thread of main interpreter — Python isn't there in CodeBench
streamlit/web/bootstrap.py _on_server_start Preview-panel auto-load + clean-shutdown via call_soon_threadsafe(server.stop)
PythonRuntime.swift SafeArray __reduce__ / __reduce_ex__ so @st.cache_data can pickle DataFrames containing numpy columns

Feature test: streamlit_test.py — 8 tabs covering text, data, charts, inputs, layout, state/cache, progress/forms, misc.

Limits on iOS

Feature Status
st.file_uploader Works for small files; large uploads may OOM
st.camera_input No AVCapture bridge — not wired
st.video Works for H.264/MP4 (WKWebView native); other codecs no
Hot-reload on save (server.runOnSave=True) Disabled — watchdog flaky in iOS sandbox
streamlit run CLI subprocess Works (no fork needed for the server loop)

Example

import streamlit as st
import pandas as pd
import numpy as np

st.title("Demo")
n = st.slider("Rows", 10, 1000, 100)

@st.cache_data
def make_data(rows):
    return pd.DataFrame({
        "x": range(rows),
        "y": np.random.default_rng(42).normal(size=rows).cumsum(),
    })

df = make_data(n)
st.line_chart(df.set_index("x"))
st.dataframe(df.head(20), use_container_width=True)

Run with either streamlit run app.py from the shell, or programmatically via streamlit.web.bootstrap.run(...) — see web-stack.md § Streamlit for the launcher pattern.