On Wednesday October 17th, we completed the switch from HTTP to HTTPS for traffic to the api.eveonline.com as announced earlier in this devblog: http://community.eveonline.com/devblog.asp?a=blog&nbid=73407.
We have also improved the API infrastructure backend.
If you run any services that utilize the API such as killboards or other services such as mentioned in the devblog and have not updated to the new API address, it will no longer be functional until you complete the update.