there is a way to create a https response with a web api with appian ?

Appian should always use https in enterprise installations - is it possible that you are using a local installation that isn't configured to run over SSL?

i create a web api but when i tested the response in a webpage it give me an error because it only receive https responses i looked in the documentation in appian and it looks the web api only give a http response

That's strange, I've never seen this behavior before. Can you provide more information about how you created / executed your Web API? For instance, are you on a cloud site / on-premise / local installation? How is your Web API defined? How did you test it?

Also can you point to the documentation that mentions that the Web API uses HTTP instead of HTTPS?

sure! https://docs.appian.com/suite/help/21.2/fnc_system_a_httpresponse.html 

i created the api object and follow the tutorial that api send a data in a json format  also im in a cloud site and i test it in sopa ui postman and it worked but in wix only allow apis with a htpps response

Ah so the "HTTP Response" described in that page in the documentation is just a generic term in Appian for the data type and does not mean that it's using HTTP instead of HTTPS. Think of it this way: we often talk about "HTTP Methods" without stating whether the actual request occurs over HTTP or HTTPS https://www.w3schools.com/tags/ref_httpmethods.asp.

If you actually go to your Web API, can you see the URL used for your API? You should see it use https

thanks! alright