What's the use case for searching for "an API" exactly? Usually, there's something very specific you want to do with an API...
In the long run hopefully a lot of the fields in the apis.json files this pulls on will be machine readable (e.g. meta-data for things like major T&C provisions), pointers to libraries etc. so you could filter on that.
We have the previous version of APIs.io supported over here: https://apimatic.io/apientity/search
Let's connect this too!
Hence the format http://www.apisjson.org (it's basically sitemap for APIs) and the search engine http://www.apis.io. The search engine is also open source so you can run your own, format is completely open.
So if we (3scale) get some benefit I won't be unhappy - but if more people start posting API info then it'll benefit everyone.