It would be awesome to have a blacklist api, with POST, DELETE, GET so that I can programmatically block and unblock domains.
For example right now I'm using Fitbit API and OpenDNS API to block Netflix unless there is 20 minutes of fitness activity reported from my Fitbit account.
This would be a good feature, and I love the example you gave! Just remember with that the device running Netflix will have probably cached the DNS records for Netflix and it might still work even though you have blocked it in Pi-Hole.
True. Cache could interfere after enabling too. The effects won't be immediate.
I'd go for a firewall rule. AS2906 Netflix Streaming Services Inc. - ipinfo.io
The Python rewrite is being built fully RESTful, so it will have support for this type of interaction.
Better late than never:
Will bring a RESTful API