An HCI professor of mine found in a small study that requiring an added plugin (Java Silverlight ext) to view certain content resulted in a greater than 50% drop in users completing the task. Users saw the requirement, didn't want to install the plugin or otherwise did not complete the task once prompted.

Obviously this isn't the case for Adobe Flash or other extremely common plugins, but I was wondering if any research or statistics were available for the effect such a requirement has on users completing a task. It's obviously an added step which always leads to losing some users but requiring a plugin seems to be a particularly lethal turn off in web apps.

  • Do you have a specific scenario in mind? Adding some detail will help you get a good answer, I think. Ease of plugin install, trustworthiness of the source, the nature of usage (casual or recurring?), and task objective will all factor into the conversion rate differential.
    – Evan
    Commented Sep 30, 2011 at 21:23
  • Perhaps I'm asking a bit too broadly, but I don't have a plan to use any such plugins so there's no specific situation I'm concerned about. Most apps I see that require plugins are video players though, maybe that would be a better scenario
    – Ben Brocka
    Commented Sep 30, 2011 at 21:31
  • I believe that any developer smart enough to do a usability study will just not use a plugin. We can all agree that using plugins can lead to lost users, so why do it. We should be able to use html + JavaScript in most cases.
    – Emil
    Commented Oct 1, 2011 at 8:39

2 Answers 2


The answer is not as simple as it first appears, as it depends on your application. In many cases, the impact is negative, as it requires the user to install software on their computer, which - for all sorts of reasons - will put many people off using this.

At the same time, for hot new plugins or popular addons, it can be a positive impact. Flash is sufficiently common that including it will probably have little or not negative impact, and ( if it is used well ) will draw people more towards your site.

Silverlight is an interesting one. It is not uncommon to need it if you use microsoft web sites. And once it has been downloaded, some people will be happy to have found a site that uses it.

Requiring a plugin is ok if most of your users will have already downloaded it. Requiring your users to explicitly download a plugin that they are unlikely to have is a real negative. Using one that your users have probably already got can be a real positive.


Unless the the UX that results from that plugin is a must for the study,the answer is: negative effect.

Actually i don't know if there are studies about that or not but its an essential approach in web application is to focus on "the availability for as much targeted users as possible."

if its necessary for functionality then adding an alternates is a good idea.it may increase development time but u'll get a solid web app. (eg.if its flash add javascript).

In all cases it depends on your targeted audience and your ability to develop alternates. finally,adding a small notification that shows the required plugin(link to it) and why we need it here will be nice and effective.

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