Hint

🧠 Not sure how to start building this file converter with Streamlit?

Here’s how you can break it down step by step:

1. Set up your app with Streamlit

import streamlit as st
st.title("CSV ↔ Excel Converter")

1. Add a file uploader that accepts both CSV and Excel:

uploaded_file = st.file_uploader("Upload a CSV or Excel file", type=["csv", "xlsx"])

1. Detect the file type based on the filename:

if uploaded_file.name.endswith(".csv"):
    # Handle CSV
elif uploaded_file.name.endswith(".xlsx"):
    # Handle Excel

1. Read the file with pandas:

   • For CSV: pd.read_csv(uploaded_file)

   • For Excel: pd.read_excel(uploaded_file)

2. Convert to the other format and create an in-memory file:

   • Use BytesIO() for Excel output.

   • Use .to_csv() with .encode() for CSV output.

3. Show the data with st.dataframe(df)
   And provide a st.download_button so users can download the converted file.

✅ That’s all it takes!
Click Show Solution to see how to tie these steps together into a clean, functional Streamlit app.