Google Custom Search API for Mobile App - Free or Paid?

[Montego via StackOverflow]

Google Custom Search (GCS) has replaced Google Search API. And all of the GCS docs are heavily weighted toward Website integration -- for adding google to your domain.

But I want to use it in a mobile app for image searches.

They offer a list API:

https://developers.google.com/custom-search/json-api/v1/reference/cse/list

But to use it requires an API key. (see docs)

To create an API key, you need to go to your cloud console and add a project. Then you can "turn on" Google Custom Search API and get a key to use.

https://cloud.google.com/console

But before enabling, a popup forces you to agree to both the Google APIs Terms of Service and the Custom Search API Terms of Service.

Google API Terms of Service https://developers.google.com/terms/

Custom Search Terms of Service: https://cloud.google.com/console/tos?id=customsearch

In the Custom Search API it clearly states, "The Custom Search API may be provided to you without any free usage quota at all. You may be charged for each successful request you make through the Custom Search API." And then links a broken link to pricing.

This is confusing to me, since Google Custom Search offers a free tier. Perhaps this is because they don't have a way of delivering ads through the API?

QUESTION: How do you integrate Google Custom Search into a mobile App via the API at the free usage tier?

If not possible, the pricing doesn't seem to line up, as it's geared towards website searches, not searches within mobile applications (where search could be a primary tool, not a secondary option). Alternatives besides Bing?

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http://stackoverflow.com/questions/20626315/google-custom-search-api-for-mobile-app-free-or-paid