Flutter Crypto App Boilerplate

A crypto tracker is real-time data plus trust

Two things define a credible crypto app: numbers that update without the user pulling to refresh, and the feeling that their data is locked down. The Flutter Kit gives you both as plumbing. A streamable price repository feeds a Cubit, so when a new quote arrives the portfolio total and every holding row repaint reactively — no manual refresh threading. On the trust side, Firebase Auth is paired with a biometric lock (Face ID / fingerprint) so re-entering the app requires the user's own face or finger. Both live behind get_it-registered services in BLoC, testable and separate from your widgets, so you can swap the data source or auth policy without touching the screens.

• Streamable price repository → Cubit → reactive portfolio UI
• Firebase Auth + biometric app lock for re-entry
• BLoC/Cubit + get_it keeps price and auth logic out of widgets
• State survives login, logout, biometric re-lock, and reinstall

Wiring real-time prices, concretely

The kit ships a repository seam rather than a hard-wired exchange, because every crypto app picks a different data provider (CoinGecko, a CEX websocket, an on-chain RPC). Prices flow through a repository interface registered in get_it and surface as a stream a Cubit subscribes to, so polling on a timer or upgrading to a websocket is a swap behind the interface, not a rewrite of your portfolio screen. The biometric gate sits on app resume, so a backgrounded app re-locks before showing balances.

class PortfolioCubit extends Cubit<PortfolioState> {
  PortfolioCubit(this._prices, this._holdings)
      : super(const PortfolioLoading()) {
    _sub = _prices.watch(_holdings.symbols).listen(_onTick);
  }
  final PriceRepository _prices;
  final HoldingsRepository _holdings;
  late final StreamSubscription _sub;

  void _onTick(Map<String, double> quotes) {
    final total = _holdings.valueAt(quotes);
    emit(PortfolioLoaded(quotes: quotes, totalUsd: total));
  }

  @override
  Future<void> close() { _sub.cancel(); return super.close(); }
}

Gating pro features behind a subscription

Crypto apps monetize on the edges — live price alerts, deeper analytics, more tracked portfolios. The kit wires RevenueCat so those become a paywall plus an entitlement check, with free trials, restore, and StoreKit 2 / Play Billing compliance handled. An EntitlementState Cubit answers 'is this user pro right now?' everywhere, so a price-alert screen or an extra-portfolio slot gates cleanly. Paywall screens theme from your Material 3 design tokens, and GA4 with consent management lets you measure which pro feature actually drives upgrades — useful in a category where conversion is fickle.

• RevenueCat gating for live alerts, pro analytics, extra portfolios
• EntitlementState Cubit — one 'is pro?' answer across the app
• Trials, restore, StoreKit 2 + Play Billing handled
• GA4 consent-managed analytics to find what converts

When a different starting point is the honest choice

Be clear about scope: this is a tracker and price-watch foundation, not a custodial wallet or an exchange. If you are building self-custody key management, signing transactions, or holding user funds, the security and compliance surface is enormous and dominated by audited crypto libraries and regulatory work that no app boilerplate addresses — that is a specialist build. If you only need a read-only price widget and have no Dart experience, a no-code tool may suffice for a v1. And if your product is fundamentally a web trading terminal, a web stack fits better than a mobile-first kit. The Flutter Kit is the right call when you want a code-first, biometric-secured crypto tracker you fully own, with real-time data wiring and subscription gating already done so you can focus on your data, charts, and alerts.

The Flutter Kit vs building a crypto tracker yourself

Frequently Asked Questions