Algolia is a French startup that provides hosted cloud search as a service with lots of developer-friendly API.
Integration is really easy regardless of what language you are using. They have 11 API clients and 4 mobile SDKs, including a WordPress plugin if you are using WordPress.
![Algolia Dashboard Algolia Dashboard](https://farm1.staticflickr.com/778/20296612804_c732f260a1_c.jpg)