Make PDFs open directly (not via download) by default

david · February 17, 2026, 9:43am

In theory, mp4 should be served inline:

lib/file_helper.rb

2d615863d


      
          # files which are safe to serve inline (no script execution risk)
          def self.inline_safe_files
            @@inline_safe_files ||= inline_images | Set.new(%w[pdf]) | supported_video | supported_audio
          end

which uses:

github.com/discourse/discourse

lib/file_helper.rb

2d615863d


      
          def self.supported_video
            @@supported_video ||= Set.new %w[mov mp4 webm ogv m4v 3gp avi mpeg]
          end

How did you achieve this? i.e. what’s the difference from unicyclist.com?

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Make PDFs open directly (not via download) by default

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