# For developers

> This page is about FlutterFlow (the app builder you use by describing your app), not FlutterFlow Studio.

URL: https://docs.flutterflow.io/ffx/for-developers

Learn what FlutterFlow builds, what you can see of your app's code, how to add packages and give the agent code, and what isn't available.

This page explains what FlutterFlow builds, what you can see of the agent's changes, and where to read more.

## What FlutterFlow builds {#what-flutterflow-builds}

Your app is a Flutter app written in Dart. FlutterFlow sets the Flutter version for every app.

FlutterFlow builds your app for phones in **Releases**, where you send builds to testers and submit them for store review.

To download a version's built files, open the version in **Releases** and choose **Files** from its menu. Only the newest finished Android build and the newest finished iPhone build keep their files, so older versions might not have any. You can download an `.apk` file and an `.aab` file for Android, and an `.ipa` file for iPhone. If a build reported why it has no `.aab` file, **Files** shows the reason. See [App files](https://docs.flutterflow.io/ffx/app-files).

## Changes {#what-you-can-see}

A thread shows the agent's changes in two places:

- **A turn's Summary:** when a turn ends, its **Summary** lists the screens, backend changes, added or removed packages, and other code that the turn changed, along with how many checks the agent ran.
- **The Changes tab:** a thread's **Changes** tab lists the thread's unpushed changes and the changes already in your app (marked **In your app**).

See [What changed](https://docs.flutterflow.io/ffx/what-changed).

## Add a package {#packages}

To add a package to your app, ask for it by name in a thread. When the turn ends, its **Summary** lists the package by name as a new add-on. See [Features and packages](https://docs.flutterflow.io/ffx/add-features).

## Give the agent code {#give-the-agent-code}

To give the agent code to work from, paste it into your message, or put it in a `.txt` file and attach the file. See [Attachments](https://docs.flutterflow.io/ffx/attachments).

## Use another backend {#other-backends}

FlutterFlow provides a built-in backend for sign-in, saved data, and uploaded files, and the agent uses it by default. If you ask for an external backend, such as Firebase, Supabase, Auth0, or your own API, the agent first offers the built-in backend. If you confirm your choice, the agent builds the external backend into your app alongside the built-in one, asks for its public settings (such as a Supabase URL and anon key), and notes that **Backend** in FlutterFlow won't show data stored there. Keep server secrets (such as service-role keys or admin tokens) on your own server rather than in your app. The agent also lists any native setup you must finish on your own computer, such as adding an Android or iOS Firebase configuration file.

## Source code {#source-code}

The agent writes and updates your app's code in threads. You can download your app's compiled phone builds from FlutterFlow, but you can't download or export its source code or send it to GitHub.

To change your app's code, ask the agent in a thread. To get your app onto phones or into the stores, use **Releases**.

## Pages for developers {#reading-list}

These pages cover what developers ask about most:

1. [What the agent can do](https://docs.flutterflow.io/ffx/the-agent): what the agent builds and checks, and what only you do.
2. [What changed](https://docs.flutterflow.io/ffx/what-changed): the turn's **Summary** and the thread's **Changes** tab.
3. [Features and packages](https://docs.flutterflow.io/ffx/add-features): ask for a feature or a package by name.
4. [Attachments](https://docs.flutterflow.io/ffx/attachments): the files you can give the agent.
5. [App files](https://docs.flutterflow.io/ffx/app-files): the `.apk`, `.aab`, and `.ipa` files for a version.
6. [Platforms and devices](https://docs.flutterflow.io/ffx/platforms): the phones and devices that your app runs on.
7. [Limits](https://docs.flutterflow.io/ffx/limits): the sizes and counts that FlutterFlow allows.
8. [Not available](https://docs.flutterflow.io/ffx/not-available): what FlutterFlow doesn't have, and what you can do instead.