Hi @miljkovicmisa, thanks for your reply!
No worries, I will try to explain better 
1- I dont intend to use the “out of the box” HubSpot forms, but create custom ones and integrate them.
2- I built a website on React and Gatsby, deployed to gatsby cloud. In order to use Hubspot forms in there, Im creating my own forms and integrating HubSpot to them. I created 4 forms, all of them work perfectly, they submit, they send data and they dont have any issues.
For that, I use a code like this in my coponents, where I add my portal and form ID supplied from HutSpot:
const handleSubmit = (evt) => {
evt.preventDefault();
var xhr = new XMLHttpRequest();
var url = 'https://api.hsforms.com/submissions/v3/integration/submit/5692042/f1905f2b-0c39-4a1f-8c96- 09c23514e92e'
var data = {
"fields": \[
{
"name": "firstname",
"value": firstname
},
{
"name": "email",
"value": email
}
],
Until here, everything works perfectly.
ISSUE:
3- When I go back to one of my working forms (is the same if I create a new one) and turn the “reCaptcha” on, then my forms spot working. (note: I dont even want to turn it on, but if I select the option “follow up”, then its mandatory to have it).
First thing: The automatic reCaptcha that is usually autogenerated in the “out of the box HubSpot form”, is not created in my custom component.
Second: if I add my own reCaptcha, now it displays and “works” (I mean, allows the user to interact and confirm that they are huamns), but the form doesnt submit, exactly the same as happened in the previous step. This takes me think that the problem is that the submit button is not storing the reCaptcha value, or expecting the one that should be “autogenerated” in the “out of the box form”, but that ll never happen as Im using my own forms.
Error:
POST https://api.hsforms.com/submissions/v3/integration/submit/5692042/f1905f2b-0c39-4a1f-8c96-09c23514e92e (400)
Probably its a simple solution, and hopefully Im simply missing something really basic that Im still now aware off!
Thanks for yout time!
Nico
@dennisedson ,