Searching a word in corpus.byu.edu seems fine.

But when I use its search service on Private mode, it gives me the following error

Sorry, but if you're in "incognito/private mode" then you need to first log in before doing a search.

How is this website able to check my browser mode?

How to get around this problem in Firefox?

  • 2
    This can be done by checking whether the FileSystem API is enabled: stackoverflow.com/questions/2909367/…. There's probably not much you can do about it since the whole point of incognito mode is to disable some features and alter the behavior of others.
    – Marc
    Commented Dec 19, 2017 at 0:29
  • 1
    @Marc, Why the browser does not provide a fake FileSystem API? Also is it the only way to detect private mode?
    – jamava
    Commented Dec 19, 2017 at 0:34
  • 1
    @jamava No, there are (literally) dozens of way to check if a system is in private mode, as well as uniquely identify said systems. This is an entire field called browser fingerprinting.
    – forest
    Commented Dec 19, 2017 at 3:02
  • @forest, it is very easy to get around user agent. Just use a random user agent generator. But user agent identifies people but not the private mode.
    – jamava
    Commented Dec 19, 2017 at 3:23
  • A random user agent actually makes you more unique due to your specific randomness distribution, among other reasons. Even if you could get around that, audiocontext fingerprinting (used by many advertising companies) can uniquely identify hardware with near 100% accuracy, regardless of the browser or operating system you are using.
    – forest
    Commented Dec 19, 2017 at 3:29


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