ElasticSearch - Elasticsearch is an open source, distributed, RESTful search engine.
Xobni - Xobni provides effortless email and address book management and search for Microsoft Outlook and BlackBerry. Put a face to every name. Lightning fast Outlook Search.
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.
Live Inbox - Live Inbox is a Microsoft Outlook plugin that helps you organize your email and search your inbox.
Citrix Gateway - Critix Gateway is a unified gateway for users that makes it easy for them to remotely access infrastructure with the help of a single sign-on across all applications.
X1 Search - X1's Lightning-Fast Search Software. Premium Alternative to Windows Desktop and Outlook Search.