Algolia - Algolia's Search API makes it easy to deliver a great search experience in your apps & websites. Algolia Search provides hosted full-text, numerical, faceted and geolocalized search.
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...
Site Search 360 - Site Search 360 enhances and improves your built-in CMS or product search with autocompletion, semantic search, filters, facets, detailed analytics, and a whole lot of customization options.
Pulno - SEO Audit and Website Analysis. Pull up your SEO.