Show HN: Stagewise (YC S25) – Front end coding agent for existing codebases
31 comments
·August 5, 2025pj_mukh
Ugh, looking for something like this for Front-end Mobile Dev (React-Native, Swift etc.). The closest thing I've found is https://www.magicpatterns.com, but that doesn't work on existing repos. Keep that in mind!
juliangoetze
The whole 'vibe-coding' space seems a bit underserved for mobile or am I wrong?
juliangoetze
Will do so!
hsundnes
If anyone is looking for a similarly great-sounding name for their startup or corporate project, I'm currently selling the domain pagewise.com
glenntws
domain squatting boohoo
zote
This is what I've been looking for! Tried self hosting the bolt.new editor to achieve something like this and it was terrible. Also interested in hearing about the SaaS you were building, I recently built something in that niche coincidentally drafted at first by v0.
juliangoetze
Haha, cool to hear!
We were tinkering with a transport management system because the industry was full of legacy software.
But before we were able to battle-test something, stagewise took off.
Still think that it's an industry worth going for (at least in Germany)
zote
Ha, this project has had me thinking about that sector more, I'll try and make an effort and go for it in the future, and congrats you have built something truly useful here.
juliangoetze
What were you building? And did it evolve/ has been used by someone?
zote
I was building something for a single logistics company; they'd handle clearing and forwarding for their clients as well as transportation if it was required, covered everything from invoicing to fleet management, outsourcing jobs, It's evolved quite a bit considering the initial premise was simply creating quotes and invoicing, maybe It'll end up being a bigger deal in the future
juliangoetze
Sounds like the experiences we've had in the industry - even though they're all 'logistics companies', their workflows and requirements differ greatly, even within a niche of a niche. This gave us a hard time building a scalable software that would be useful for as many companies in the industry as possible
wodow
Does it work with Node/JS/TS front ends only, or can it work with other languages and web frameworks?
juliangoetze
It will work as long as the project is a web project and runs in the browser. The agent is a pure js snippet and can be injected into any web app
alienbaby
existing codebases... so long as they are web applications?
juliangoetze
Yep, that's correct. stagewise only works with web applications.
aagha
Cool!
How does this work for non-UI code?
juliangoetze
Do you mean for UI-related changes that also include modifying the backend, or do you mean pure backend changes that don't involve UI at all?
koakuma-chan
How do I make an account? There is only an option to Sign In. I entered my email, it said that you sent an email, but there's nothing.
glenntws
Are you using one-time mail providers? Otherwise, please check the spam folder of course. If nothing helps, feel free to join Discord (https://discord.gg/DjMqMnUVCh) and we'll debug this together.
koakuma-chan
Hey, I received it, it just took like 10 minutes, I use fastmail
glenntws
awesome. hope you enjoy
juliangoetze
Did the agent work well after the mail came through?
koakuma-chan
I think it ran out of credits before it could finish one task.
Available plugins: @stagewise-plugins/angular
Agent server initialized successfully
Stagewise is running on http://localhost:4200
Proxying app from port 3100
Opening browser...
Credits: [ ------------------------------ ] 1.99/2€
Credits: [ ------------------------------ ] 1.97/2€
Credits: [ ------------------------------ ] 1.95/2€
Credits: [ ------------------------------ ] 1.92/2€
Credits: [ ------------------------------ ] 1.89/2€
[multiEditTool] Editing file public/i18n/en.json (30679 bytes)
[multiEditTool] Edit 0: Replaced 1 occurrence
[multiEditTool] Edit 1: Replaced 1 occurrence
[multiEditTool] Edit 2: Replaced 1 occurrence
[multiEditTool] Edit 3: Replaced 1 occurrence
Credits: [ ------------------------------ ] 1.86/2€
juliangoetze
Hmm, the initial credits are usually enough to do 4-5 major tasks and a few more smaller ones. Was the log with 1.86/2 credits the latest?
juliangoetze
The Sign In option also serves as Sign Up.. I'm having a look at the email issue now!
artahian
v0 and lovable have way too much hype, I think what you're doing with stagewise (i.e. being dev-first instead of optimizing for non-developer users) is the real long term use of AI.
glenntws
thanks for the kind words! If you have ideas or wishes for next steps, feel free to share.
fahaad
[dead]
Hey HN, we're Julian and Glenn, and we're building stagewise (https://stagewise.io), a frontend coding agent that lives inside your browser on localhost and operates on local codebases.
You can spawn the agent into locally running web apps in dev mode with `npx stagewise` from the project root. The agent lets you then click on HTML Elements in your app, enter prompts like 'increase the height here' and will implement the changes in your source code.
Before stagewise, we were building a vertical SaaS for logistics from scratch and loved using prototyping tools like v0 or lovable to get to the first version. But when switching from v0/ lovable to Cursor for local development, we felt like the frontend magic was gone. So, we decided to build stagewise to bring that same magic to local development.
The first version of stagewise just forwarded a prompt with browser context to existing IDEs and agents (Cursor, Cline, ..) and went viral on X after we open sourced it. However, the APIs of existing coding agents were very limiting, so we figured that building our own agent would unlock the full potential of stagewise.
Here's how it works: When you run `npx stagewise`, our cli proxies your running web application in dev mode and injects a toolbar containing the coding agent on top of it. Each prompt you send will be enriched with browser context and sent to our cli, which will call our backend and modify the source code of your local codebase accordingly.
Here's a demo of our agent changing the login UI of Cal.com, a popular open-source meeting scheduling app: https://www.youtube.com/watch?v=BkDcAozK9L4.
So far, we've seen great adoption from non-technical users who wanted to continue building their lovable prototype locally. We personally use the agent almost daily to make changes to our landing page and to build the UI of new features on our console (https://console.stagewise.io).
If you have an app running in dev mode, simply `cd` into the app directory and run `npx stagewise` - the agent should appear, ready to play with.
We're very excited to hear your feedback!