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← Build things with code · Mission 3 of 18

Turn a Python script into a web app you can share

Streamlit turns a short Python file into a real web page with sliders, dropdowns, file uploads, charts and download buttons. You'll have a working quote calculator in your browser within ten minutes, then build a sales dashboard and put it online for free. No HTML, no JavaScript.

30 minBeginnerTools: FreeStep 1 free
Tested 9 Oct 2026 · Streamlit 1.65.0 and pandas 3.0.6 on Python 3.12 via uv 0.11.9, Edge, Windows 11
Streamlit installed in its own project folder, with its usage statistics switched off before the first run
A freelance quote calculator with a number box, a slider, a dropdown and a tick box, that remembers the quotes you save
A sales dashboardupload a CSV, get totals, a bar chart and a table, and download the result
  • Both apps working at phone width, and the steps to share them on your Wi-Fi or put them online free at a .streamlit.app address
Before you start
  • Windows, Mac or Linux, with about 300MB of free disk space (the project folder comes to about 274MB)
  • uv installed. It's a small, official tool that installs Python apps cleanly. Step 1 shows you how
  • Notepad or any code editor. You'll paste the code, not write it from scratch
  • No Python experience. If you can change a word in quotes, you can change these apps
01/06Install Streamlit0 done
STEP 01 of 06~4 min

Install Streamlit

Streamlit lives in its own project folder, so it can't clash with anything else on your PC.

  1. Streamlit ↗ is a free, open-source Python library. You write an ordinary script, and every st. line becomes something on a web page: a heading, a slider, a chart, an upload box. When someone clicks, Streamlit runs your script again with the new values.

  2. You install it with uv. If you don't have it yet, install it first, then close the terminal and open a new one:

    Windows (only if you don't have uv)
    winget install --id astral-sh.uv -e
    Mac or Linux (only if you don't have uv)
    curl -LsSf https://astral.sh/uv/install.sh | sh

  3. Now make a project folder called my-apps with Streamlit inside it. Run these one at a time:

    Terminal
    uv init --python 3.12 my-apps
cd my-apps
uv add streamlit
    Output
    Initialized project `my-apps` at `...\my-apps`
Using CPython 3.12.13
Creating virtual environment at: .venv
Resolved 38 packages in 471ms
Downloading pyarrow (26.7MiB)
...
Installed 37 packages in 4.46s
...
 + pandas==3.0.6
...
 + streamlit==1.65.0
...

  4. It takes about 15 seconds on a decent connection, and the project folder comes to about 274MB. Streamlit brings its own helpers with it, including pandas (for tables of data) and Altair (for charts), so there's nothing else to install.

    Terminal
    uv run streamlit version
    Output
    Streamlit, version 1.65.0
    TipEvery command in this mission starts with uv run. That tells uv to use the Streamlit inside this folder, so always cd my-apps first when you open a new terminal. uv also made a main.py file. You can ignore it.
✓
Checkpointuv run streamlit version prints Streamlit, version 1.65.0 (or newer).
If it breakserror: Failed to spawn: streamlit and program not found
error: Failed to spawn: streamlit and program not found
You're not in the project folder. Run cd my-apps (from the folder you made it in) and try again.
Still stuck? Ask the community
Next mission · Build things with codeWhere did my money go? Explore your spending in a Python notebook that turns into an app
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