Microsoft announce Visio Online. This allows you to view Visio diagrams in a browser, working in a similar way to the other Office Online tools – but with no editing capabilities.

You can find the announcement here: http://bit.ly/2lRUb7u and for information on which Office 365 licences include Visio Online (most of them) and which browsers are supported (many) then go to this FAQ page: http://bit.ly/2lNzusK.