You can create recaptcha secret key and site key for localhost. While creation of recapcha you have to give site URL as following.
| 1 | 127.0.0.1 (or) localhost |
| Specified domain | Website domain | Will reCAPTCHA work? |
|---|---|---|
| yoursite.com | yoursite.com | Yes |
| www.yoursite.com | Yes | |
| subdomain.yoursite.com | Yes | |
| subdomain.yoursite.com:8080 | Yes |
Recapcha key and secret for localhost (or) Testing purposes.
Site key : 6LeIxAcTAAAAAJcZVRqyHh71UMIEGNQ_MXjiZKhI
Secret key : 6LeIxAcTAAAAAGG-vFI1TnRWxMZNFuojJ4WifJWe
Source