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.

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.flutter-io.cn in the process. End of 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 is useful if you need to trigger validation, reset the widget, or destroy it programmatically.

CaptchaConfig parameters #

This is an immutable configuration for Web SmartCaptcha.

The term "Web SmartCaptcha" refers to the underlying HTML page hosted inside the WebView that instantiates and executes the Yandex SmartCaptcha JavaScript widget.

Parameter	Required	Default	Description
`clientKey`	✔		The client-side key passed to Web SmartCaptcha.
`language`		`ru`	The language for the Web SmartCaptcha UI.
`alwaysShowChallenge`		`false`	Whether the CAPTCHA should always display a challenge. Useful for testing.
`useInvisibleMode`		`false`	Whether to run CAPTCHA in invisible mode – without the "I'm not a robot" checkbox.
`badgePosition`		`bottomRight`	The position of the Data Processing Notice (DPN) badge when `useInvisibleMode` is `true`.
`hideBadge`		`false`	Whether to hide the DPN badge when `useInvisibleMode` is `true`.
`useWebViewMode`		`true`	Whether to enable specialized mobile WebView optimization mode.
`initialScale`		`1.0`	The initial scale factor for the Web SmartCaptcha content.
`allowUserScaling`		`false`	Whether the user can scale the Web SmartCaptcha content using gestures.
`maximumScale`		`3.0`	The maximum scale factor when `allowUserScaling` is `true`.

YandexSmartCaptcha parameters #

Control the SmartCaptcha's runtime lifecycle, Flutter-level UI customizations, and callback registration.

Parameter	Required	Default	Description
`config`	✔		The configuration for this CAPTCHA instance.
`onChallengeSolved`	✔		Called when the user successfully solves a CAPTCHA challenge.
`backgroundColor`		`null`	The background color of the widget container.
`loadingIndicator`		`null`	A custom widget displayed while the Web SmartCaptcha content is loading.
`onCaptchaReady`		`null`	Called when the CAPTCHA script is fully loaded and initialized.
`onChallengeShown`		`null`	Called when the CAPTCHA challenge popup becomes visible.
`onChallengeHidden`		`null`	Called when the CAPTCHA challenge popup is hidden.
`onTokenExpired`		`null`	Called when the CAPTCHA token expires or is invalidated.
`onNetworkError`		`null`	Called when a network error occurs while loading or executing the CAPTCHA.
`onJavaScriptError`		`null`	Called when an uncaught JavaScript error occurs inside the CAPTCHA WebView.
`onNavigationRequest`		`null`	Called when a navigation request is made inside the WebView.
`controller`		`null`	A controller to programmatically interact with the CAPTCHA.
`baseUrl`		`null`	A valid HTTP(S) base URL for SmartCaptcha content. Required for domain validation and resolving origin policy issues.

CaptchaController methods #

Provide access to the Web SmartCaptcha's imperative methods.

Method	Description
`execute()`	Starts user validation.
`reset()`	Resets the Web SmartCaptcha widget to its initial state.
`destroy()`	Removes the Web SmartCaptcha widget and its associated event listeners.

Screenshots #

SmartCaptcha in a simple test screen:

The initial state of the Yandex SmartCaptcha container with the 'I'm not a robot' checkbox.

The initial state of the Yandex SmartCaptcha pop-up, featuring a challenge for the user to solve.

The state of the Yandex SmartCaptcha container with the 'I'm not a robot' box checked, after the user successfully solved the challenge.

SmartCaptcha in a real-world application:

The initial state of the Yandex SmartCaptcha container with the 'I'm not a robot' checkbox, as seen in a real-world application.

The initial state of the Yandex SmartCaptcha pop-up, featuring a challenge for the user to solve in a real-world application.

yandex_smart_captcha 7.2.4
yandex_smart_captcha: ^7.2.4 copied to clipboard

Metadata

Yandex SmartCaptcha for Flutter #

Motivation #