Hello, I am trying to make Home Assistant work with IFTTT through Google Assistant on my phone. Hass is installed on my Raspberry Pi, under my local network (though I also have port forwarding enabled, so I can access outside of my network). I’ve followed the tutorial on how to integrate IFTTT and Webhooks to create an applet, but the application is unable to complete a post. I’m using “http://my_local_ip:8123/api/services/switch/turn_on?api_password=my_password” on the URL field in IFTTT and “{” entity_id":“switch.main”} on the body. Content type is “application/json”. But when I try to make a post through Tasker for example, it works just fine. I don’t know what I’m doing wrong 
You cannot use local IP address on IFTTT. Your HA needs to be available outside the home network for IFTTT webhooks to work.
So, if I want this thing to work, I just have to use a DNS server like NoIP and use my hostname as the address in IFTTT? Even when my phone is on the same network? I just tried to do this, but I’m now getting an unknown protocol error (I’ll try to upload a screenshot)
You want the IFTTT servers to be able to reach your HA. Since they are not in your network, you will have to some DDNS provides (e.g., DuckDNS) with your HA. You should be able to use that URL in a browser and reach your HA instance.
You don’t ”have to” no, just depends how brave you are. If you’ve done the port forward as you say you have you just use your external IP not your internal device one. Whatismyip.com of you don’t know.
However, if your ISP is providing you with a dynamic IP address as most do unless you specifically ask/pay for one, you’ll have to change your ifttt settings each time it changes. This is where noip and DuckDNS come in as you can set them to auto update do you don’t need to change anything.