Best way to ban users at the device level

Actions & Logic

Hi FF gang,

Looking for suggestions on blocking repeat scammers - when we detect suspicious activity, we disable the scammer’s account at the Firebase level. However, these scammers often have access to hundreds of purchased Gmail accounts. We already use email verification and are considering adding phone verification, but ideally, I’d like to collect a persistent device identifier that remains intact across app reinstalls and factory resets. I know there are services like FingerprintJS and Shield, but these are pretty expensive, and given where we're at, I'm looking for a more cost-effective approach.

Has anyone successfully managed this issue?

What have you tried so far?
  • Email verification

  • Blocking users at the Firebase installation ID level (requires them to reinstall the app, but savvy scammers bypass this easily)

  • Considering OTP phone verification

Did you check FlutterFlow's Documentation for this topic?
No
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