As Gopal (Vembu) mentioned, REST API's have taken over simpler HTTP API's. However, REST runs over HTTP/S and support's URI's, in a GET format request, which may blur the lines since HTTP API's are just a GET request with a URI... Not suggesting to market your product in an ambiguous manner though.
Anyways, to try and answer your question, it is hard to find a product with an HTTP API but REST API's can be just as easy to use as an HTTP AP. In fact they can be exactly the same if you implement your API with simple URI's that perform a function.
https://restfulapi.net/http-methods/ Opens a new window
https://restfulapi.net/resource-naming/#:~:text=1.3.-,URI,intuitive%20and%20easy%20to%20use. Opens a new window
Here are some products I am aware of the have/had an HTTP API:
Xbox Media Center (XBMC) which is now Kodi used to have an HTTP API but moved to a JSON/RPC API.
https://en.wikipedia.org/wiki/Kodi_(software) Opens a new window
Rovio robot toy released in 2008 had an HTTP API.
https://en.wikipedia.org/wiki/Rovio_(robot) Opens a new window
Amazons API Gateway still supports an HTTP API.
https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api.html Opens a new window