I was splitting a check at dinner last week and thought, I could just build this. Ten minutes later I had a working tip calculator on my phone.
Not a mockup. Not a prototype. A real app I texted to the group and everyone added to their home screens.
Here's how that works.
You describe it
Open Envelope. Type what you want in plain English. "A tip calculator that splits the bill, handles tax, and lets you round up." That's it. No wireframes.
The AI reads your description and builds a working app. Real UI, real logic, real interactivity. You watch it happen.
You tweak it
The first version is never exactly right. That's fine. You chat with the AI: "Make the buttons bigger. Add a dark mode. Actually, let people save their default tip percentage."
Each change takes a few seconds. It's like pair programming with someone who types really fast and never gets defensive about feedback.
You ship it
Hit publish. You get a link like envelope.build/tip-split. Text it to someone. They tap it, add it to their home screen, and now they have a full-screen app.
No app store. No download. No "please update to the latest version." Just a link that works.
Why this actually works
Envelope builds Progressive Web Apps. PWAs work offline, look native, and install from a URL. Your users don't know or care that it's a web app. They just see an icon on their home screen that does the thing.
We handle the boring parts: generating the manifest, resizing icons to the right PWA sizes, writing the service worker, showing the right install instructions for iOS vs Android.
You handle the interesting part: deciding what your app should do.