I'm building a proprietary application that loads into its WebView a remote, self-hosted GPLv2 licensed web application.

I'm sure that loading a resource via WebView will not violate GPL (the web browsers do it all the time).

The problem is I want to also inject some CSS styles (which are distributed with the properiatary app) into the WebView that hosts the remote GPL content. The CSS styles may target ids/classes specific to the GPLed web app.

My questions:

  1. Is it ok to inject CSS like this, or is this violation of GPL?
  2. If it's not ok, what if I generate the CSS at runtime, character by character. I.e. each character of the css would be an element of an array and then joined and injected.
  3. My question is about GPLv2, but out of curiosity - would this be any different for GPLv3 and AGPL?
  4. (similar to 2) - what if the CSS is hosted remotely and the app downloads it at runtime? (and later stores the css file in user data directory).

To answer possible questions:

  • The GPL app is self-hosted and I have permissions to use it, so this is purely a software licensing question - it's not like I'm embedding someone elses web app
  • I cannot apply CSS modifications to the GPL app directly for various reasons (and it's not that I don't want to release those tiny modifications, it's a technical issue). The styles have to be injected from my proprietary app
  • You say you have permission to use it already (from the author), so is your Question whether or not your proposal would be OK, even if you didn't have permission, but only had the permissions the GPL v2 gives you?
    – Brandin
    Jul 27, 2021 at 13:42
  • "it's not like I'm embedding someone elses web app" - It sounds to me like that's what you're doing (even if you host it on your own server, it is still the app authored by the GPL-licensed software). Of course, that is probably OK if you follow the license terms.
    – Brandin
    Jul 27, 2021 at 13:43
  • I don't have explicit permissions. It's a distributable GPL web app. Everyone has permissions to self-host it under GPL. And by self-hosting I mean it will be self-hosted on a remote server and is not shipped along with the proprietary app. My question is only about whether I can inject some CSS into the WebView that loads the remote GPL web app and have this CSS bundled with the proprietary app. Jul 27, 2021 at 16:29


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