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let's say I am using Tailwind CSS (licensed under MIT) in my website by using the npm package "tailwindcss" which on build creates a css file. According to MIT - "The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.".

The css file that is created has a comment on top "/* ! tailwindcss v3.0.23 | MIT License | https://tailwindcss.com */"

Is that sufficient? or do I need to include the whole MIT text or do I need to make a /license page and write about it there "tailwindcss is used in this website, licensed under MIT - full MIT license here"? if not, how do I do it correctly?

I saw some sites like this which seem to use tailwindcss but in the devtool sources only have the top line in the css "tailwindcss v3.0.23 | MIT License | https://tailwindcss.com" is that a violation of the MIT license?

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    See also opensource.stackexchange.com/questions/9258/…
    – Brandin
    Dec 31, 2022 at 5:28
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    Since it's on Github and distributed via npm (their web site tells you to install it via npm), you could claim that it is a bug in the distribution. Probably they should either modify the minification process to exclude that MIT notice from minification, or they should arrange that the npm install process also installs a copy of the license in a separate file.
    – Brandin
    Dec 31, 2022 at 5:35
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    Alternatively they might simply change the link in the minified version to point to a page containing the actual license. The current hyperlink only points to the tailwind landing page, which doesn't mention the license anywhere. Since it's a web project, including a hyperlink to a page where the actual license text is reproduced might arguably be considered as "including" the license in the copy.
    – Brandin
    Dec 31, 2022 at 5:38
  • See also this discussion in TailwindCSS repository: github.com/tailwindlabs/tailwindcss/discussions/11094
    – Mitar
    Feb 29 at 11:30

3 Answers 3

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This is a point where common web development practices deviate from the actual text of the license. The minified CSS file contains the text “MIT License”, but not the actual text of the license as required by the license:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

In all likelihood, nothing will come from this, especially if the minified CSS file was provided by the Tailwind project itself.

However, to be safe, you should fulfil the actual license conditions instead. For example:

  • You could edit the CSS file to include a license header.
  • You could collect all open source licenses that you rely on into a separate “credits” page that is reachable e.g. via your site footer. Such separate pages are more common in mobile apps, though, and I've never seen this on a website. There are tools such as yarn licenses generate-disclaimer that can generate such pages from package metadata, though I don't think it can help in this specific case.
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    thanks for answering, I will go with the "credits" page then. Also I found sites that include licenses in a /license page, for example - this
    – hdtk
    Dec 31, 2022 at 13:18
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The creator of TailwindCSS claims that they do not hold any copyright over the output:

I've thought terribly hard about — my instinct is that it's important to me that the license and copyright notice are included when making a copy or derivative of Tailwind CSS the tool (made up of files like this one), but that the generated CSS is generally yours, not ours.

There's a bit of a gray area here with things like preflight which is a considerable chunk of CSS code that becomes part of your project, but I'm not personally bothered by that.

Candidly it's not important to me that the generated CSS contains any mention of Tailwind or our license for legal purposes at all, we only add it there because it's a helpful way to tell when a site is using Tailwind and what version it's on, and not even for any particular data analysis reasons or anything, just because it's fun to celebrate when we see a cool new site that's built with Tailwind.

Not sure if such an answer can be seen as legally enforceable.

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I am not a lawyer, but I am not sure if CSS output should even have a MIT license? Isn't this like compiled output from a compiler? The license of the compiler does not apply to the compiled output?

I think the fact that TailwindCSS adds that banner is misleading and they should not be doing that.

And if you say that in the case of TailwindCSS it combines pre-made (licensed) parts together, then I say that compilers do that as well. A compiler has a pre-made part for how to convert a for loop in C into assembly, for example.

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    As RubberDuck notes in a comment on our relevant canonical question, "There are a few notable exceptions to this. A big one is parser generators like ANTLR and Bison. An ANTLR grammar is copied into the output of the grammar and Bison copies a large portion of itself into the output. In fact, Bison has a special exclusion from this part of the GPL because of this.". Whether such is the case with this CSS generator, I can't say, but it's worth noting the exception to your rule.
    – MadHatter
    Feb 29 at 12:03

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