Show HN: FastApps – zero-boilerplate framework for building ChatGPT apps

Posted by zachpark on Saturday October 18, 2025 @01:12AM
from the show-hn dept.

https://www.fastapps.org

Building interactive widgets for ChatGPT turned out to be way more complex than I expected. Between the MCP protocol, widget registration, build setup, CSP policies, and resource serving — I kept writing the same boilerplate over and over just to get something basic working.

That’s why I built FastApps, an open-source framework that lets you build ChatGPT apps with only two files: a Python backend and a React frontend.

It removes all the glue code and focuses on developer experience:

- Auto-discovers and registers MCP widgets automatically

- Builds and bundles React UIs with zero config

- Manages CSP, metadata, and resource serving out of the box

- Type-safe data flow with Pydantic and React hooks

- Runs as an MCP server, fully compatible with ChatGPT and other MCP clients

If you’ve been experimenting with MCP or building ChatGPT tools, I’d love your feedback. It’s fully open source — and I’m looking for contributors who want to help shape this ecosystem together.

GitHub → https://github.com/DooiLabs/FastApps

Docs → https://www.fastapps.org/

( 9 comments | 2 points | on HN )

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by rosaaie on Saturday October 18, 2025 @01:17AM (#45625101)

looks promising. So is this basically just a codegen tool or scaffolding to save some boilerplate or is it an actual runtime framework that keeps running alongside the chatgpt?

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by zachpark on Saturday October 18, 2025 @01:19AM (#45625110)

It’s an actual runtime, not just scaffolding. FastApps runs as an MCP server and it handles widget registration, protocol messages, static assets, and the data flow between backend and frontend.

When you run fastapps create, you get a running service that ChatGPT talks to over MCP, not just a code template. You can extend or deploy it like any other web app.

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by rosaaie on Saturday October 18, 2025 @01:21AM (#45625120)

Makes sense. How opinionated is it about the frontend? I saw React in the docs or can I use something else?

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by zachpark on Saturday October 18, 2025 @01:22AM (#45625123)

Right now it's React-first because the Apps SDK UI layer is React-based. But the frontend is bundled automatically, so if OpenAI expands support for other frameworks later, swapping it out would be straightforward.

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by freakynit on Saturday October 18, 2025 @05:10AM (#45625990)

This is really well done.

Any scope for backend-only part? Also, couldn't find examples for nodejs.. is it supported?

Thanks..

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by zachpark on Monday October 20, 2025 @12:01AM (#45640109)

Right now FastApps mainly focuses on Python-based backends.

Could you share a bit more on what you mean by “backend-only"? Are you thinking of running logic without any UI part?

Node.js isn’t supported yet, but I’d love to hear your use case!

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by freakynit on Monday October 20, 2025 @02:23PM (#45647303)

Cool... and yes.. without the UI part.

Nodejs use-case: I'm just more comfortable in it. Nothing else :)

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by donebydone on Saturday October 18, 2025 @04:24AM (#45625808)

Oh nice. I actually thought about building something similar. Did you benchmadk the one Vercel made for nextjs?

[ Parent | on HN ]

Re:Show HN: FastApps – zero-boilerplate framework for buildi... by dohyun1m on Sunday October 19, 2025 @02:18AM (#45632343)

Hi I'm David, Co-founder of FastApps! Yes we did benchmark Next.js support for ChatGPT apps. We figured out there was nothing like it for python.

Apps in ChatGPT is based on MCP servers, and as you know many people develop mcp servers in python. So we believe that FastApps would be the best choice for people who are building ChatGPT apps in python.

[ Parent | on HN ]