There have been multiple times in which the developer community’s reverse-engineering of a Google service via an unpublished API has led to great things. The Google Maps API, for example, became a formal supported API months after seeing what creative engineers could do combining map data with other data sources. We currently support more than 80 APIs that developers can use to integrate Google services and data into their applications.
However, there are some times when using an unsupported, unpublished API also carries the risk that the API will stop being be available. This is one of those situations.
We built autocomplete as a complement to Search, and never intended that it would exist disconnected from the purpose of anticipating user search queries. Over time we’ve realized that while we can conceive of uses for an autocomplete data feed outside of search results that may be valuable, overall the content of our automatic completions are optimized and intended to be used in conjunction with web search results, and outside of the context of a web search don’t provide a meaningful user benefit.
In the interest of maintaining the integrity of autocomplete as part of Search, we will be restricting unauthorized access to the unpublished autocomplete API as of August 10th, 2015. We want to ensure that users experience autocomplete as it was designed to be used — as a service closely tied to Search. We believe this provides the best user experience for both services.
For publishers and developers who still want to use the autocomplete service for their site, we have an alternative. Google Custom Search Engine allows sites to maintain autocomplete functionality in connection with Search functionality. Any partner already using Google CSE will be unaffected by this change. For others, if you want autocomplete functionality after August 10th, 2015, please see our CSE sign-up page.
Posted by Peter Chiu on behalf of the Autocomplete team