The first thing you want to consider before implementing your search is the backend you're going to use for your data.
Search UI works best with Elastic App Search and Elasticsearch.
If you're relatively new to the search problem or Elastic ecosystem, we recommend choosing App Search. It solves many search problems out-of-box and is generally simpler to start with, althought it's not as flexible as Elasticsearch.
On the other hand, if you prefer flexibility over simplicity and already familiar with Elasticsearch, go with it! Just note that our Elasticsearch connector is still in technical preview and its API might change in the future.
If you're still not sure, go with App Search. It'll help you start quickly, and you can switch to Elasticsearch later if you need to.
Search UI also works with Elastic Workplace Search and Elastic Site Search.
Choose Site Search if you are already using Swiftype, these are basically a single product with two names. Otherwise, it's best to go with the App Search connector, since the functionalty of Site Search has already been implemented in the App Search's web crawler.
It is possible to implement your own connector to Search UI. Read our Custom connector guide to learn more.