Verifying the user's response

This page explains how to verify a user's response to a reCAPTCHA challenge from your application's backend.

For web users, you can get the user’s response token in one of three ways:

• g-recaptcha-response POST parameter when the user submits the form on your site
• grecaptcha.getResponse(opt_widget_id) after the user completes the reCAPTCHA challenge
• As a string argument to your callback function if data-callback is specified in either the g-recaptcha tag attribute or the callback parameter in the grecaptcha.render method

For Android library users, you can call the SafetyNetApi.RecaptchaTokenResult.getTokenResult() method to get response token if the status returns successful.

Token Restrictions

Each reCAPTCHA user response token is valid for two minutes, and can only be verified once to prevent replay attacks. If you need a new token, you can re-run the reCAPTCHA verification.

After you get the response token, you need to verify it within two minutes with reCAPTCHA using the following API to ensure the token is valid.

API Request

URL: https://www.google.com/recaptcha/api/siteverify

METHOD: POST

API Response

The response is a JSON object:

{
  "success": true|false,
  "challenge_ts": timestamp,  // timestamp of the challenge load (ISO format yyyy-MM-dd'T'HH:mm:ssZZ)
  "hostname": string,         // the hostname of the site where the reCAPTCHA was solved
  "error-codes": [...]        // optional
}

For reCAPTCHA Android:

{
  "success": true|false,
  "challenge_ts": timestamp,  // timestamp of the challenge load (ISO format yyyy-MM-dd'T'HH:mm:ssZZ)
  "apk_package_name": string, // the package name of the app where the reCAPTCHA was solved
  "error-codes": [...]        // optional
}

Error code reference