Flutter

For Flutter, the widget embeds the EU CAPTCHA in a WebView in the app and supplies an interface in Dart.

Requirements

The following requirements must be met:

Requirement	Value
Flutter	From version 3.0
Dart SDK	From version 3.0
Operating system	Android from API level 19, iOS from version 13
Credentials	Public sitekey from the Details view

Enter the dependencies

Add these entries to the pubspec.yaml file:

dependencies:
  flutter_inappwebview: ^6.0.0
  http: ^1.2.0

Copy the lib/eucaptcha.dart file and the assets/ directory into your project, and enter the files:

flutter:
  assets:
    - assets/euc_check.all.js
    - assets/euc_styles.css

Set up the platforms

For Android, add this entry to the android/app/src/main/AndroidManifest.xml file:

<uses-permission android:name="android.permission.INTERNET"/>

For iOS, no more settings are necessary.

Embed the widget

import 'eucaptcha.dart';

EuCaptcha(
  sitekey: 'EUCAPTCHA_SITE_KEY',
  theme: 'auto',   // 'light', 'dark', or 'auto'
  lang: 'en',      // BCP 47 language code
  onComplete: (response) {
    // response is the token — submit to your server as "eu-captcha-response"
  },
  onExpire: (_) { /* CAPTCHA expired */ },
  onError:  (_) { /* error occurred  */ },
)

The theme value controls the appearance with light, dark, and auto. The lang value takes a language code as specified in BCP 47.

Reset the widget

Use a GlobalKey<EuCaptchaState> to call reset():

final _captchaKey = GlobalKey<EuCaptchaState>();

EuCaptcha(key: _captchaKey, sitekey: '...', onComplete: ...)

// later:
_captchaKey.currentState?.reset();

Verify the token

After the onComplete call, send the token to your server. The server verifies the token:

POST https://api.eu-captcha.eu/v1/verify
Content-Type: application/json

{
  "sitekey":           "EUCAPTCHA_SITE_KEY",
  "secret":            "EUCAPTCHA_SECRET_KEY",
  "client_ip":         "<client IP>",
  "client_token":      "<token from widget>",
  "client_user_agent": "<user-agent>"
}

The response is { "success": true, "train": false }.

See Verify a client token.