While Algolia offers front-end libraries to facilitate every step of search implementation, you can use Algolia to perform searches from your back end.
Algolia recommends a front-end search implementation—that is one that queries Algolia directly from your end users’ browsers or mobile applications. That said, you may want to implement back-end search because you do some server-side pre-processing or have other reasons for wanting all search traffic to pass through your servers.
The most direct way to implement back-end search is to use the officially supported back-end API clients. You can also use the InstantSearch libraries through your back end.