How to Add Google reCAPTCHA to Odoo Forms (v15/v16)?

[Vihan Richard]

I'm currently trying to implement Odoo Google reCAPTCHA on our website's contact and signup forms to prevent bot submissions. I've explored a few modules, but I’d like to know:
What’s the most stable way to add Odoo reCAPTCHA (v2 or v3) without breaking custom templates?

Is there a built-in solution or must I use a third-party module?
Can I extend this to backend forms like portal registration?
Also, does anyone have experience integrating Odoo captcha with custom controllers or JSON-RPC endpoints?

Looking for advice on maintaining UX without compromising bot protection. Any insights, sample code, or module suggestions would be helpful.
Thanks in advance!