End user documentation tools – knowledge base / manual

Hi folks, any recommendations for end user documentation i.e. knowledgebase / FAQ / Manual for a cloud based SAAS?

On another project we've used a customer support tool to hold the guidance but the issue with that is anyone could access it including customers as it was hosted separately to our system.

I'd rather not tie up dev time with creating something bespoke so wondering if there are any tools that anyone can recommend.