> ## Documentation Index
> Fetch the complete documentation index at: https://assembly.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

The app builder takes a plain-English description and produces a real, working app installed in your workspace. You open it by clicking **+ Add App** in the sidebar and describing your app in the prompt box. (Under **More ways to add**, **Browse all apps** and **Embed existing content** are where you add existing built-in apps and embeds: see [Built-in apps](/docs/built-in-apps/introduction) and [Embeds & links](/docs/embeds-and-links/introduction).)

The build process has a shape worth understanding before you start, so you know what's happening when you're in the middle of it.

## The build loop

<Steps>
  <Step title="You write a prompt">
    A few sentences describing what the app does and who uses it. Specificity helps; over-specifying implementation doesn't. See [Writing initial prompts](/docs/building-new-apps/writing-initial-prompts).
  </Step>

  <Step title="The app builder interviews you">
    A short Q\&A — usually one to three questions — to fill in the gaps. The app builder asks only what it needs and skips what it can decide on its own.
  </Step>

  <Step title="The app builder returns a plan">
    A one-page summary of the app: what it does, who uses it, the core flows, the notifications. You can edit the plan in the chat or accept it and move on.
  </Step>

  <Step title="The app builder builds the app">
    A few minutes of work. You'll see tasks progressing and a live preview. Some apps pause for your input — to approve a sensitive task, or to collect an API key for a service the app uses.
  </Step>

  <Step title="The app builder installs the app">
    The app appears in your workspace, ready to use. You can keep iterating in the same chat.
  </Step>
</Steps>

## What the app builder can build

Apps that fit inside the Assembly portal model:

<Check>
  Client-facing apps that live in the Portal
</Check>

<Check>
  Internal tools for your team
</Check>

<Check>
  Apps that use Assembly's CRM, auth, notifications, and branding
</Check>

<Check>
  Apps that store their own data (each app gets its own database)
</Check>

<Check>
  Apps that call external APIs (with credentials you provide)
</Check>

<Check>
  Apps that use AI features (routed through Assembly's AI proxy)
</Check>

## What the app builder can't build

Some categories are outside what the app builder is designed for. If you describe one of these, it will tell you up front and suggest an alternative.

<AccordionGroup>
  <Accordion title="Publicly accessible experiences">
    Marketing sites, public landing pages, public forms, public directories. Apps you build live behind authentication — only signed-in internal users or signed-in clients can reach them.
  </Accordion>

  <Accordion title="Native mobile, desktop, or hardware apps">
    The app builder produces web apps that render inside the Assembly Dashboard and Portal. iOS, Android, desktop, and hardware integrations aren't in scope.
  </Accordion>

  <Accordion title="Real-time streaming">
    Live video, voice, WebRTC, or sub-second collaboration. Your apps are interactive but not streaming-grade.
  </Accordion>

  <Accordion title="Heavy compute">
    ML training, large-scale data processing, video transcoding, anything that needs more than a typical web app's resources.
  </Accordion>

  <Accordion title="Apps that fight Assembly's chrome">
    The Dashboard and Portal have a fixed sidebar with the app rendered in the main area. Apps that need to take over the full viewport or hide the sidebar won't work.
  </Accordion>

  <Accordion title="Things Assembly already does">
    If your idea is essentially the Messages app, the Payments app, or another built-in, the app builder will suggest the existing app from **Browse all apps**. You can still build custom if you want — it just won't pretend the built-in doesn't exist.
  </Accordion>
</AccordionGroup>

## Build time

Most builds finish in a few minutes. Larger apps with more flows and more integrations take longer. The build chat shows progress in real time, and you can leave the tab and come back without losing state.

<Tip>
  Don't try to build the entire app in one prompt. Start with the core flow, get it working, then iterate. Smaller builds finish faster, fail less, and give you something to test against earlier.
</Tip>

## Next

<CardGroup cols={2}>
  <Card title="App templates" icon="grid" href="/docs/building-new-apps/app-templates">
    Starting points organized by category.
  </Card>

  <Card title="Writing initial prompts" icon="pen" href="/docs/building-new-apps/writing-initial-prompts">
    What to include, what to leave out, and examples.
  </Card>
</CardGroup>