How to securely use api key
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I am going to make a simple web app.  It will only have a few pages at most, and the main focus of the app is making calls to an api and doing stuff with that info.

I want to know what the best way is to keep my api key secure.  Are there extremely lightweight frameworks that I can use for this?  Should I just create a php page at the root?  I could build something with codeigniter, but that seems like it is too much for what I need.

Thanks!