This might not be a Google Captcha, but it is at least still here and working. The history is that the functionality was created before other captchas (like reCaptcha) was offered to humanity.
All captchas are valid in 5 minutes after requesting them.
Getting the captcha
Using captchas are currently free of usage. The API module is quite simple built: Requesting a captcha from /3.0/captcha/ will return a hash and an image url. You can also call for the captcha with /captcha/getCaptcha (works for APIv2 also).
The getCaptchaResponse looks like this:
"date": "2018-07-14 09:52:48"
|Response Parameter Key||Response Parameter Value|
|imageUrl||The URL that you want to display as an image src on your site|
|imageHash||The hash string linked to the imageUrl, that must be used when testing the captcha|
|date||Indicates from which date and time the captcha and string has been created (from this date/time the captcha is valid in 5 minutes)|
Example of a captcha rendered by the captchaApi:
By running /captcha/getCaptcha, your response will instead be something like below:
Test the captcha string
Testing this string against the captchaApi is being made either through
Or with a GET-request immediately (which is not recommended) like this: /3.0/captcha/testcaptcha/hash/theImageHashString/response/theImageContentString
Also, a simple HTTP post request to /3.0/captcha/testcaptcha works, where the body could look like this
In this case, the response of this query will be:
If the control instead fails, the response will throw back an exception with error code 2003: TAPI_PLUGIN_CAPTCHA_STRING_MISMATCH
"faultstring": "Captcha test failed"
Get the image for a specific hash
As the URLs above reveals, getImage() is used to show a generated captcha image. Using /getImage/<hashString> will give you the image. For the example below, you'll get "test", since hashes expires after 5 minutes and will not be available for viewing after this.