Elyse - The free version allows up to 30 tags.

LogikCull - Logikcull is a discovery automation platform that helps expedite and lower the cost of litigations & investigations.

DEVONthink - DEVONtechnologies develops DEVONthink, DEVONagent, and other Mac and iOS apps for document and information management and web research.

Nextpoint - Nextpoint offers solutions for eDiscovery, evidence exchange, deposition and transcript management.

Leap - With Leap you find things based on your natural memory of that file.

Exterro - Exterro offer eDiscovery and legal software solutions.