Maybe approach Qlik Sales or a Qlik Partner, they can often be amenable to supplying a trial Qlik Sense server licence, if they feel it will help secure a sale.
Having a trial Server licence will also help you to evaluate the server side parts of the Qlik Sense product, as well as the End User experience.
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Another thought though, have you looked at the Qlik Cloud ?
I used it during our evaluation process and it allowed me spin up a Qlik Sense app on it & share it to 5 users via the web - albeit very manual and no end user reloads. But I also span up a freebie web server on the Google cloud, knocked up a basic web site and embedded into it an iframe from the Qlik Cloud. Then I also embedded in this freebie web site an iframe from a weather web site alongside the Qlik iframe which impressed people as weather affactes our operations. Admittedly this was all a bit of manual toy, but I quite enjoyed it and it impressed those with the cheque book and loosened their wallets.
This was a couple of years ago - so no doubt the freebie Qlik Cloud has changed, but I doubt it has gone backwards.
I also knocked a basic mashup on my laptop with Qlik Sense Desktop - those with the cheque books loved that, especially as I done it with the Bootstrap framework to adapt responsively to different screen resolutions, so with the Chrome debugger I could emulate it running in iPhone mode with it auto adjusting responsively to the limited screen real estate of a smart phone.
Shame in a way that they were impressed and bought it, as I was quite enjoying spinning up freebie things and and learning how everything worked.
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P.s. Maybe just ask them not to fiddle with the script and viz objects, but thereagain they may be incorrigible fiddlers, like me, who just cannot resist. But if they do fiddle and break things, you can just give them another virgin unbroken copy.
