Let's start with couple of words on captcha's algorhytm, let's see what traffic and at which point is being sent.
1. User enters the page and the recaptcha form is uploaded from google
2. User clicks the checkbox and solves the captcha
3. When the captcha is solved, google checks the answer and returns code to the user in the field <textarea id="g-recaptcha-response"
4. User fills all the forms on the page
5. User sends these forms. At the same time code is sent from the field "g-recaptcha-response"
6. Site receives data from the users and sends a request to google to check code's validity from the field "g-recaptcha-response"
7. Google checks the validity of the code. If the code is valid the site continues processing user's data.
Recaptcha solving scheme:
1. You fill all the needed fields
2. You send us Site_Key from the site + additional data ( optional: URL of the page, where you've encountered the captcha, PROXY that you use)
3. We upload captcha to our server and assign a worker to solve it
4. When the worker solves his captcha we receive g-recaptcha-response
5. We return g-recaptcha-response to you
6. You enter our answer into the field g-recaptcha-response and pass the form
Where do I get and where do I input the data?
Browse HTML-code of the page, where you've encountered the captcha:
1. Find this parameter
This is site's key, it is constant and unique for each site (unless admin changes it manually)
Return the key back to us as parameter sitekey=%data-sitekey%
2. Find the field for text
<textarea id="g-recaptcha-response" name="g-recaptcha-response" class="g-recaptcha-response" style="width: 250px; height: 40px; border: 1px solid #c1c1c1; margin: 10px 25px; padding: 0px; resize: none; "></textarea>
You will need to enter our answer here