Can I add a blacklist or whitelist access to the API web service?

Yes, for you to add a list of 5 IP addresses to allow access to our API web service you need to login https://app.captchas.io/clients/v2/login and go directly to settings https://app.captchas.io/clients/v2/settings and add the IPs you want to grant access to our API web service.

No IP list means anyone from anywhere you are, you can use access the API web service without problem, as long as you provide your correct API key.