@fingerprintchecker/react-native

React Native module for FingerPrintChecker. It is a thin wrapper over the native Android and iOS SDKs and exposes one operation: identify, the v2 flow. Your backend creates an intent with the secret key, the app passes the intent token to identify, and your backend verifies the returned attestation.

Requires React Native 0.76 or later.

Install

npm install @fingerprintchecker/react-native
cd ios && pod install

Expo: it works in a development build or after expo prebuild. It does not work in Expo Go, because it contains native code.

Use

import { FingerPrintChecker } from '@fingerprintchecker/react-native';

const fp = new FingerPrintChecker({ publishableKey: 'pk_...' });

// intentToken comes from your backend, which created the intent with the secret key.
const result = await fp.identify(intentToken, { linkedId: 'user-123', tags: { plan: 'free' } });

if (result.ok) {
  // Send result.attestation to your backend, which verifies it.
  // visitorId and the score fields are present only when the project
  // enables score details; otherwise they are undefined.
  await sendToBackend(result.attestation);
} else {
  console.warn(`identify failed: ${result.reason} (${result.httpStatus})`);
}

identify never rejects; every outcome is { ok: true, ... } or { ok: false, reason, httpStatus }. Do not decide anything from the app alone: the backend verifies the attestation.

Config

publishableKey (required), baseUrl, powDifficulty, integrityProbes. Android only: cloudProjectNumber, integrityTimeoutMillis. iOS only: useAppAttest, useDeviceCheck. A field the current platform does not have is ignored.

baseUrl must be https. Plain http is accepted only for localhost, 127.0.0.1 and ::1.

Errors

reason is passed through unchanged from the native SDK. The wrapper adds these:

| reason | meaning | |---|---| | bad_config | empty publishableKey; baseUrl that is not a valid URL; baseUrl that is not https (plain http is accepted only for localhost, 127.0.0.1 and ::1); or powDifficulty outside 8 to 28 | | bad_intent_token | the intent token is empty | | invalid_tags | tags holds something that is not a string, number, bool, null, or a list or object (string keys) of those | | not_linked | the native module is missing: rebuild the app after installing, run pod install, and avoid Expo Go | | bridge_error | any other unexpected failure on the native side |

Platform notes

• Android: minSdk 23. To use Play Integrity, set cloudProjectNumber in the config.
• iOS: your React Native version's minimum (15.1 for React Native 0.76). App Attest needs the App Attest entitlement on your own app. The privacy manifest ships with the pod.

Example

A runnable app is in the repository under react-native/example.