Does Confluence enable to share documents with an external audience (people outside the company)

[Robert Massaioli (Atlassian)]

Since you have Confluence Cloud maybe you would like "Instant Websites" for public consumption.

This is a pretty cool looking add-on.

[Nick Reilingh]

You can also use a plugin like Comala ShareIt to create temporary read-only links to pages within an access-controlled space.

[Robert Ortner]

should be possible  if you give at least one space anonymous permissions 

spacetools/permissions

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