st.download_button

Display a download button widget.

This is useful when you would like to provide a way for your users to download a file directly from your app.

Note that the data to be downloaded is stored in-memory while the user is connected, so it's a good idea to keep file sizes under a couple hundred megabytes to conserve memory.

Function signature[source]
st.download_button(label, data, file_name=None, mime=None, key=None, help=None, on_click=None, args=None, kwargs=None, *, type="secondary", disabled=False, use_container_width=False)
Parameters
label (str)	A short label explaining to the user what this button is for. The label can optionally contain Markdown and supports the following elements: Bold, Italics, Strikethroughs, Inline Code, and Emojis. This also supports: Emoji shortcodes, such as `:+1:` and `:sunglasses:`. For a list of all supported codes, see https://share.streamlit.io/streamlit/emoji-shortcodes. LaTeX expressions, by wrapping them in "$" or "$$" (the "$$" must be on their own lines). Supported LaTeX functions are listed at https://katex.org/docs/supported.html. Colored text, using the syntax `:color[text to be colored]`, where `color` needs to be replaced with any of the following supported colors: blue, green, orange, red, violet, gray/grey, rainbow. Unsupported elements are unwrapped so only their children (text contents) render. Display unsupported elements as literal characters by backslash-escaping them. E.g. `1\. Not an ordered list`.
data (str or bytes or file)	The contents of the file to be downloaded. See example below for caching techniques to avoid recomputing this data unnecessarily.
file_name (str)	An optional string to use as the name of the file to be downloaded, such as 'my_file.csv'. If not specified, the name will be automatically generated.
mime (str or None)	The MIME type of the data. If None, defaults to "text/plain" (if data is of type str or is a textual file) or "application/octet-stream" (if data is of type bytes or is a binary file).
key (str or int)	An optional string or integer to use as the unique key for the widget. If this is omitted, a key will be generated for the widget based on its content. Multiple widgets of the same type may not share the same key.
help (str)	An optional tooltip that gets displayed when the button is hovered over.
on_click (callable)	An optional callback invoked when this button is clicked.
args (tuple)	An optional tuple of args to pass to the callback.
kwargs (dict)	An optional dict of kwargs to pass to the callback.
type ("secondary" or "primary")	An optional string that specifies the button type. Can be "primary" for a button with additional emphasis or "secondary" for a normal button. Defaults to "secondary".
disabled (bool)	An optional boolean, which disables the download button if set to True. The default is False.
use_container_width (bool)	An optional boolean, which makes the button stretch its width to match the parent container.
Returns
(bool)	True if the button was clicked on the last run of the app, False otherwise.

Examples

Download a large DataFrame as a CSV:

import streamlit as st

@st.cache_data
def convert_df(df):
    # IMPORTANT: Cache the conversion to prevent computation on every rerun
    return df.to_csv().encode('utf-8')

csv = convert_df(my_large_df)

st.download_button(
    label="Download data as CSV",
    data=csv,
    file_name='large_df.csv',
    mime='text/csv',
)

Download a string as a file:

import streamlit as st

text_contents = '''This is some text'''
st.download_button('Download some text', text_contents)

Download a binary file:

import streamlit as st

binary_contents = b'example content'
# Defaults to 'application/octet-stream'
st.download_button('Download binary file', binary_contents)

Download an image:

import streamlit as st

with open("flower.png", "rb") as file:
    btn = st.download_button(
            label="Download image",
            data=file,
            file_name="flower.png",
            mime="image/png"
          )

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