You can install this add-on https://www.concrete5.org/marketplace/addons/recaptcha...

Then setup your keys and add the captcha to your form.

Thanks for your answer.

Forgive my basic question, but how to access the form? (I have never used concretet5)

Try by logging in, going to the page that the form appears on, and editing that block.

Ok, I have installed the add-on that you recommended me. Later I generated and placed the keys in "captcha configuration".

But I do not know how to add it, I'm in the domain.com/contact section and I do not see a "block" called "captcha" or "recaptcha". How is it added?

It's not a separate block, it's part of the form block. There should be a setting in there "Solving a CAPTCHA Required to Post?" or something similar. You set it to Yes and it will show the captcha on the form.

I do not see the option anywhere. When I try to edit the block, an HTML editor opens. How should I do to add it with HTML?

I attached an image. If I click on the first option "edit block" I get the HTML editor that I mentioned earlier.

I have also attached a screenshot of the HTML editor.

If that's an HTML block it's going to be very complicated to add the captcha, I'm sorry I can't give you directions on how to do that here.

Your message is "hopeless". Why can not you pass me the HTML tag?


PD: I have used quotes because I am using a translator, maybe it translates poorly.

Unfortunately this isn't something you can just add to the front end, you also have to add the code to the part of the code that this form posts to that checks the value of the captcha in order to verify that it was filled out properly.

Since this isn't a Concrete5 from there is no way for me to guide you where to put the code that checks the submission.

I hope i can shed some light on your question even though its many months ago.
Ive just discovered how to add google reCaptcha on my site, although not sure its actually doing anything.
Once you have installed the free add-on from concrete5 site, and registered with google to get your private and secret keys, you need to go into your sites systems settings and under 'Captcha Setup' you should see option to use reCaptcha version instead of standard concrete 5 version.
You will need to add your keys (the ones from the google registration) and a few more self explanatory settings.
Save this then go back to the page where you added the form, and then edit the form. Once in edit mode make sure 'Solving a CAPTCHA Required to Post?' is selected, and save form, then come out of edit mode.
Refresh your page and you should see the reCAPTCHA logo somewhere on your page, probably at the bottom, which indicates its active.
Im going to go back to the google registration page for re-cpatcha and check my site URL is correct as i think this must be 100% correct for it to work.

Hope this helps anyone like me who discovers things by persistence only, haha!