[SideburnsOfDoom]

In case anyone is wondering, there are ways to use API keys securely, i.e. without sending them in plaintext on each request.

One common way is OAuth signed requests: http://hueniverse.com/2008/10/beginners-guide-to-oauth-part-... There should be an OAuth library for the language that you are using.

[jcromartie]

Ways like HTTPS?

[SideburnsOfDoom]

That is a different way. Which is most appropriate when is commented on here: https://news.ycombinator.com/item?id=7371484