I'm confused as to what this license really means.

Say I have a large piece of software I plan on selling and keeping closed source. It makes use of several small resources that are under the MIT license.

Do I just have to copy paste each MIT license with their names in it into the source code? That seems pointless since it will remain closed source.

If the software is distributed by a service like Google Play which only takes a .apk file there's no way to distribute the license with the software, if that's what you're supposed to do.

So in this case would using those small resources licensed under MIT not be allowed? Or what?

Also, in the license text, what does "substantial portions of the Software" mean? Which software? The software that is licensed under MIT? Or any other new software using this MIT licensed software?

I'm quite confused as you can tell, so it would be nice if someone could clarify some of this for me.

EDIT: Additionally, how would someone be able to tell what parts of the code were licensed under MIT? If they are able to tell that somehow, how would they be able to tell which person made that specific portion?


There seems to be a misconception with how to comply with the MIT license. Here's the relevant sentence, and only condition in the license apart from the warranty disclaimer:

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

You can include the license text in your source file. If you do, and if you distribute your software as source code only, as some OSS do, the license text is automatically visible and right there with the MIT-licensed code. But if you distribute binaries, the license text (typically) gets compiled away, therefore you are no longer fulfilling the single condition in the license. What you need to do is include the license with your binary distributions, maybe as a text file, or embedded in the program's about dialog. For most distribution channels, there's some way of including the source code license(s). For an Android example, look at Settings > About > Legal Information > Open source licenses and enjoy.

As for what "substantial portion of the software" means, it refers to the MIT-licensed code. See this question for what "substantial portion" means: How much is "substantial portion" in MIT licence?

Additionally, how would someone be able to tell what parts of the code were licensed under MIT? If they are able to tell that somehow, how would they be able to tell which person made that specific portion?

If you don't follow the MIT license, you are violating copyright. It's true that it's hard to prove copyright violation if you don't have access to source code, but a court can compel you to divulge your source code so that a judgement can be made. If you've genuinely and blatantly violated copyright, it will be very easy to prove.

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  • If I do include the MIT license attached to the binary, how would any person know which part of the program is under the MIT license, and which is proprietary, given that it's all compiled together? (Assume I'm coming from the standpoint of a programmer who has used something that is MIT licensed but wants to keep their own additions completely restricted. That is, I'm worried that people will think that the MIT license applies to the entire binary, instead of just the little snippets of code I used.) – Pro Q Sep 7 '19 at 4:50
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    @ProQ In that case it's probably best to include a message in an additional text file and/or in the software's user interface, explaining that portions of the software are Copyright (c) <year> <your name>, and other portions are Copyright (c) <year> <licensor's name> and MIT-licensed. – jkdev Jun 29 at 22:48
  • @congusbongus, you're saying a website needs to have an about page which shows the attribution? Case law citation needed. – Pacerier Aug 24 at 6:45

Are you perfectly sure that you will never want to transfer this code to someone else? If you ever want to sell it, or license it, or have a change of heart and make it open source, you'll need to be able to document the provenance. If you throw out all the copyright and license information, you'll be up a creek. If you work for a company, the company should have a policy of this kind just in case the whole place gets sold.

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