Typesense is an open source, typo tolerant search engine that delivers fast and relevant results out-of-the-box. Typesense has been built from scratch to offer a delightful, out-of-the-box search experience. From instant search, to autosuggest, to faceted search, Typesense has got you covered. A couple of highlights:

Typo Tolerance: Handles typographical errors elegantly, out-of-the-box. Simple and Delightful: Simple to set-up, integrate with, operate and scale. Blazing Fast: Meticulously architected from the ground-up for low-latency instant searches. Tunable Ranking: Easy to tailor your search results to perfection. Faceting & Filtering: Drill down and refine results. Grouping & Distinct: Group similar results together to show more variety of results. Scoped API Keys: Generate API keys that only allow access to certain records. Curation & Merchandizing: Pin particular records to a fixed position in search results, to highlight them. Raft-based Clustering: Setup a distributed cluster that is highly available.

Also offers a hosted SaaS offering that runs the same open source version.