---
title: "Discussion on \"How I Refactored a Streamlit Prototype into a Modular Python Application\" | Hashnode"
description: "Discussion on \"How I Refactored a Streamlit Prototype into a Modular Python Application\". What building a real project taught me about separation of concerns, testable business logic, and designing a prototype for what comes next."
url: "https://hashnode.com/posts/how-i-refactored-a-streamlit-prototype-into-a-modular-python-application/6aa278beb6c8152e34da1025"
---

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# [How I Refactored a Streamlit Prototype into a Modular Python Application](https://aderayodevnotes13.hashnode.dev/how-i-refactored-a-streamlit-prototype-into-a-modular-python-application?utm_source=hashnode&utm_medium=feed)

What building a real project taught me about separation of concerns, testable business logic, and designing a prototype for what comes next.

Sep 10 · 7 min read · aderayodevnotes13.hashnode.dev  
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## Written by

[Aderayo Olamide Adelanwa](https://hashnode.com/@deraintech)

@deraintech · Lagos, Nigeria

  
[View profile](https://hashnode.com/@deraintech)

Technical Research & Systems | Backend Engineering • Data Systems • AI Applications • Building in Public

Researcher, consultant and philosopher working at the intersection of research, technology including computation, AI, data and software systems, and human judgment. My current work combines years of research experience with growing expertise in backend software engineering.

## Responses 2

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[Ale](https://hashnode.com/@alessandrof)

[Sep 10](https://hashnode.com/posts/how-i-refactored-a-streamlit-prototype-into-a-modular-python-application/6aa278beb6c8152e34da1025/comment/6aa2d37fb3641d627bea0de7)

The transition from a single-file Streamlit script to a modular structure is the exact tipping point where a prototype becomes a real product. Decoupling core business logic from the Streamlit rendering layer not only makes writing unit tests far easier, but it also gives you the flexibility to expose that same logic via FastAPI or a CLI later on without a complete rewrite.

In other words: moving business logic out of the presentation layer is a game-changer for long-term maintainability. Once you had everything decoupled into modules, did you add a test suite with pytest, or was the focus mainly on making the Streamlit UI cleaner to extend?

[Aderayo Olamide Adelanwa](https://hashnode.com/@deraintech)

[Sep 11](https://hashnode.com/posts/how-i-refactored-a-streamlit-prototype-into-a-modular-python-application/6aa278beb6c8152e34da1025/comment/6aa2d37fb3641d627bea0de7#reply-6aa3f23e90af396790ee23ce)

Thank you for your reply, yes the intention was to ensure that there is enough flexibility to expose that same logic via FastAPI or a CLI later on without a complete rewrite. To your question, yes i added a test suite with pytest for each of the files in addition to making the streamlit UI cleaner to extend.