flutter_variants

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A Flutter SDK for safe UI variants.

flutter_variants lets you change approved UI values such as text, labels, and design copy without shipping a new app release. Layout, navigation, callbacks, API calls, payments, authentication, and business logic stay in the Flutter app.

This is not a server-driven UI renderer. It is a small variant slot system.

Minimal example

Wrap your app with VariantHost to load variant values from a JSON URL:

VariantHost(
  url: Uri.parse(
    'https://your-domain.com/apps/my_app/production/variants.json',
  ),
  child: const App(),
)

Embed slot widgets where the values should flow in. Each slot always has a local fallback, so the UI keeps rendering when values are missing, invalid, or the server is unreachable:

const VariantText(
  id: 'home.title',
  fallback: 'Welcome',
)

Example variants.json:

{
  "home.title": {
    "type": "text",
    "value": "Try the new onboarding"
  }
}

For tests, previews, and dev-time overrides, slot widgets can also be fed directly via VariantScope — see DOCUMENT.md.

Documentation

See DOCUMENT.md for the full developer guide:

• Philosophy and the slot-based approach
• API reference (VariantScope, VariantText, VariantButtonLabel, VariantImage, VariantIcon, VariantColor, VariantSpacing, VariantEdgeInsets, VariantBorderRadius, VariantString, VariantBool, VariantNumber, VariantTextStyle, VariantVisibility)
• VariantHost configuration (timeout, retry, refresh, cache, callbacks)
• Self-hosting and the variants.json format

Contributing

Contributions are welcome — see CONTRIBUTING.md for the dev setup, code conventions, and hard rules to respect.

Running the example

cd example
flutter run

Running tests

flutter test
cd example
flutter test

If you use FVM, prefix the commands with fvm:

fvm flutter test
cd example
fvm flutter test