What are some alternatives?
When comparing Helpie Knowledge Base Wiki Plugin and ProProfs Knowledgebase, you can also consider the following products
MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
ZenDesk - Zendesk is a beautiful, lightweight help-desk solution.
DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
Document360 - Self-service knowledge base software focused on SaaS Products & Enterprise Software Projects.
AMuseWiki - Amusewiki is more than just a wiki engine, it’s also a powerful authoring, archiving and publishing platform.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community