Rocket.new App to Google Play: Build the AAB Without Installing Flutter

Rocket.new builds web apps (Next.js by default) and Flutter mobile apps. For a mobile app it can build an APK you install on a phone, but for Google Play its own guide has you download the project and build the AAB on a Mac or PC with Flutter installed. If you do not want to set up Flutter, upload the downloaded project to a cloud Flutter build and get a signed AAB back. If your Rocket project is a web app, wrap its published URL instead; see URL to APK.

What Rocket gives you

Sources: Rocket's Android APK and Google Play publishing docs, checked October 3, 2026.

Build the AAB from the downloaded project

1. In Rocket, open the Code tab and download the project as a .zip.
2. Open env.json and replace Rocket's placeholder values with your real ones, such as your Supabase URL and anon key. Rocket exports it as a template; a placeholder builds without an error but fails on the phone.
3. Check the ZIP: the project at its root or inside one top-level folder, with pubspec.yaml, your Dart source, declared assets, pubspec.lock if the ZIP has one, and env.json (below), but no private signing keys. The source build guide lists what a build needs.
4. Create a source project in Code2Native, choose Google Play, and upload your keystore if you already have one for this app. Without one, Code2Native creates a signing key for the project and keeps it for every build; every later update must use the same key.
5. Upload the ZIP. The build log shows each step, and you get a signed AAB to upload to Google Play.

Keep env.json in the ZIP

Rocket keeps the keys your app connects with, such as Supabase's, in env.json, and the app reads them at build time through Flutter's --dart-define-from-file. Without that file the app still builds, but sign-in, data and AI features get empty values and fail on the phone. When env.json sits at the project root as a JSON object of strings, numbers and booleans, Code2Native's Flutter build passes it the same way, and the build log lists the names it passed, never the values. Leave it out of the ZIP to build without it.

If the app signs in with Google, Google checks the certificate the app is signed with. Rocket's guide registers the fingerprint shown for its own APK; the app Google Play installs is signed with Play's app signing key instead. Add the SHA-1 fingerprints from Play Console (App integrity: the app signing key and the upload key) to the Android OAuth client in Google Cloud, or Google sign-in fails on that app.

Those values end up inside the app, as they do when Rocket builds it, and anyone with the app can read them. Supabase's anon key is meant for that when Row Level Security is on for your tables; never put the service_role or another secret key in env.json. An AI provider's API key is better kept on a server your app calls.

Before the build starts, the ZIP is checked for some problems that would stop it, such as a project type we do not build or a Flutter setup below Google Play's target API level, and those are refused before a build credit is spent. If your project sets an older target, see Flutter target API 36.

What it costs

Source builds need Builder ($39/month) or Pro and spend included credits. The builder makes logged compatibility adjustments but cannot fix missing application code, and a compile error in your project does not refund the credit; a platform fault does. Check that your project is supported before you buy.