As the title says, am I allowed to use other web applications from my own one (to generate data or to convert files), even though they don't provide an API (which I had to build myself), as long as their terms don't explicitly forbid such behavior?

I know it is a short description, but the question really is that simple. I could not find the answer elsewhere.

Thank you in advance.

1 Answer 1


If their terms don't prohibit it and you are accessing their resources responsibly and through regular channels, there's no reason to think it would be s problem. That said, you should reach out to the owners of those apps anyway for at least two reasons:

  1. To alert them to your plans and ask permission and for any instructions to avoid causing issues. Worst case, you get no answer and are back at square 1. Otherwise, you know where you stand and don't have to worry.

  2. Leaving aside the legal aspect - you don't want to take a dependency whose owner is unaware of that dependency. I mean, if you want your app to work at easy every now and then.

  • Ok, thank you for this answer. What do you mean by "Accessing their resources through regular channels"?
    – Aspie96
    Aug 16, 2016 at 8:01
  • 1
    @Aspie96 Adhering to their terms of service as closely as possible, accessing the site like it was intended to be accessed. So if the service was meant to be accessed through a browser by logged-in users, then you should use HTTP requests, crawl through visible links, and restrict your behaviors to those that would be possible for a logged-in user to generate. So, no calling a service a thousand times a second if a logged in user would have to click a button and no looking for unlinked resources.
    – Patrick87
    Aug 16, 2016 at 18:45
  • Got it, thanks. The reason I asked is that those applications are, of course, intended to be used by humans and not by other applications. But yes, I do the same HTTP requests a human user would do using the proper forms (without actually using the form, of course).
    – Aspie96
    Aug 17, 2016 at 20:07

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