Yandex SmartCaptcha for Flutter

This package makes it easy to integrate Yandex SmartCaptcha into Flutter mobile apps. To learn more about the Yandex SmartCaptcha service, visit its official page.

This package was inspired by flutter_yandex_smartcaptcha, but it offers several improvements, including bug fixes, slightly better performance, enhanced documentation, and a much cleaner API.

Motivation

One day at work, I urgently needed to integrate a Yandex CAPTCHA into a mobile app, and the flutter_yandex_smartcaptcha package came to the rescue. However, I discovered a serious bug and reported it to the author. When they didn’t respond, I decided to create a similar package myself and learn how to publish packages on pub.dev in the process. The end of the magnificent story.

Usage

Super simple! Here’s the most basic example:

YandexSmartCaptcha(
  config: CaptchaConfig(
    clientKey: 'your-client-key',
  ),
  onChallengeSolved: (token) {
    // Handle the solved captcha token
  },
)

In most cases, you’ll only need the YandexSmartCaptcha and CaptchaConfig classes. The CaptchaController is entirely optional – it's useful if you need to trigger a challenge popup programmatically, but that’s rare.

Configuration parameters

Parameter	Required	Default	Description
clientKey	✔		The client-side key passed to the Web SmartCaptcha.
alwaysShowChallenge		false	If true, the user will always see a challenge.
language		ru	The language for the Web SmartCaptcha UI.
invisibleMode		false	If true, the CAPTCHA runs in invisible mode – without the "I’m not a robot" checkbox.
hideDPNBadge		false	If true and invisibleMode is enabled, the badge linking to the Data Processing Notice (DPN) will be hidden.
dpnBadgePosition		bottomRight	If invisibleMode is enabled, this option specifies the position of the DPN badge.
webViewMode		true	If true, the CAPTCHA runs in a special WebView mode, improving challenge accuracy on mobile devices.
initialContentScale		1.0	The initial scale factor for the Web SmartCaptcha content.
userScalableContent		false	If true, the user can zoom in and out of the Web SmartCaptcha content.
maximumContentScale		3.0	If userScalableContent is enabled, this defines the maximum scale factor for the content.
backgroundColor		null	The background color of the YandexSmartCaptcha widget.

✱ "Web SmartCaptcha" refers to the underlying HTML document, hosted in a WebView, that runs the Yandex SmartCaptcha JavaScript code.

Screenshots

1. SmartCaptcha in a simple test screen:

2. SmartCaptcha in a real-world application: