[Scarbutt]

If your app is a web app this is a no brainer, the users browser could simply do the print or PDF conversion as needed.

That's arguable, IME (and also a better UX), most would prefer to just get the PDF file which just one click than to deal with additional browser dialogs. No everyone knows how to do print-to-pdf or even know it exists.

Or do you mean browsers expose print-to-pdf functionality as an API?

[SigmundA]

Hitting print in the browser or calling Window.print() if you want to force the dialog.

If you serve a PDF you still need to hit print or use dialog to save, you can use a headless browser server side to serve that if needed.

I do think browser could use better print API's but you not getting around that with server side PDF's unless the server direct prints to on site printers or something.