wa_number_checker 0.1.2

Check whether a phone number is registered on WhatsApp (and/or WhatsApp Business) via on-device contact sync. Android-only; iOS returns unsupported.

wa_number_checker

Check whether a phone number is registered on WhatsApp (and/or WhatsApp Business) via on-device contact sync. Built for registration forms: type a number, get a warning-level answer — never a blocker.

final checker = WaNumberChecker();

final ok = await WaPermissionGate.ensureReady(
  context,
  appName: 'MyApp', // your app's name, shown in the rationale dialog
  purpose: 'verfied your number WhatsApp for One Time Password',
);
if (!ok) return;

final r = await checker.verify('0822...');
if (r.isValid) {
  // registered — detectedBy tells which app: {whatsapp, whatsappBusiness}
} else if (r.status.isUncertain) {
  // pending / offline / storageBlocked — neutral, let the user continue
} else {
  // notRegistered / waNotInstalled / waNotActive —soft warning
}

Live form helper (debounce + cache + cancel, safe in onChanged):

validator = WaInputValidator(checker: checker, onResult: (r) {
  setState(() => result = r); // submit button stays enabled
});
TextField(onChanged: validator.onChanged);

How it works

1. checkExisting() — read-only lookup via PhoneLookup, free even in power-save.
2. If missed, checkWithInsert() — inserts a temporary contact into a dedicated account (com.wa_checker.temp, never Google cloud), watches RawContacts with a ContentObserver, and reports registered with detectedBy once WA/WA Business sync picks the number up.
3. The temp contact is deleted afterwards (autoCleanup: true by default).

Number normalization (08xx/+62/62 → 62xx) is shared between Dart and Kotlin. Inserts are rate-limited (1 per 10s) and always run off the UI thread.

Honest limitations

• Android-only. iOS always returns WaCheckStatus.unsupported.
• Sync-based, not real-time. Expect ~seconds of delay; default timeout is 15s. Treat the result as a hint for a warning label, not a security gate.
• Timeout is neutral. pending means "could not determine", not "invalid". Do not block registration on it — retry on submit / app resume.
• Writes a temporary contact to a dedicated on-device account and deletes it after the check (autoCleanup). No data leaves the device, nothing is sent to any server by this package.
• Permissions merged into your app: READ_CONTACTS, WRITE_CONTACTS, ACCESS_NETWORK_STATE, GET_ACCOUNTS, plus <queries> for com.whatsapp / com.whatsapp.w4b. You must show a prominent disclosure (see WaPermissionGate.ensureReady) and justify contacts access in Play Console, or your app update can be rejected. The package itself requests nothing silently.

API layers

• Simple (most consumers): verify(), WaInputValidator, WaPermissionGate.
• Advanced: checkExisting(), checkWithInsert(), cancel(), getDeviceInfo(), dispose().

See example/ for a registration-form demo. Field-tested on Samsung/OneUI with Google-default storage and power-save on.