Display a download button widget.

Download button has a few constraints:

  • Download button is designed to download data that is stored in the Streamlit server's memory and works best when file size is reasonably small, <50MB.
  • For large file sizes, it is recommended to use a third party cloud based object storage solution.
  • We recommend doing any file transformation operations outside the download button declaration. Caching such transformations also prevents from slowing down the app on every rerun. See the examples below to learn more.
Function signature

st.download_button(label, data, file_name=None, mime=None, key=None, help=None, on_click=None, args=None, kwargs=None)

Parameters

label (str)

A short label explaining to what this button is for.

data (str or bytes or file)

The contents of the file to be downloaded.

file_name (str)

An optional string to use as the name of the file to be downloaded, eg. 'my_file.csv'. If file name is not specified, then we provide a generic name for the download.

mime (str or None)

The MIME type of the data. If None, defaults to "text/plain" or "application/octet-stream" depending on the data type.

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.

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