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Let's say i used a MIT program as a base for a new project, and modified about 50% of the program files.

  • How should i specify that the program is a derivative work?
  • Do i need to keep track of every file i modified and explicitly say the changes made?
  • If i use a portion of two MIT licensed programs in the same file, alongside with a modification, how should i specify that?

1 Answer 1

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The MIT license is so simple, you should be able to find the answer to your questions by just reading it. It has only one requirement:

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

This means that you have no obligation to specify that a program is a derivative work, nor to track the modifications that you made.

For merging several MIT licensed software, you just have to copy the various notices (that is copyright statement + text of the license). If the license texts are exactly the same (the authors did not alter the original MIT license), then it is acceptable to just put the text of the license once, after the various copyright statements. E.g.

Copyright (c) 2017 Your Name
Copyright (c) 2015-2016 Previous Developer's Name
Copyright (c) 2014-2016 Other Project Developer's Name

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

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

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
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  • What if the author says to use MIT license but doesn't include one in his source code?
    – jeffery
    Jan 5, 2021 at 23:10
  • example if it applies: gist.github.com/ashleydavis/f025c03a9221bc840a2b
    – jeffery
    Jan 5, 2021 at 23:10
  • You could encourage the author to add a license header to their gist, although there you can consider that you have a clear written authorization from the author to reuse under the terms of a well-known license.
    – Zimm i48
    Jan 7, 2021 at 10:22
  • 1
    This works when your project is going to be MIT licensed, but could you clarify how to only give them copyright of the modified files? For instance if I have a GPL licensed project and I'm using two files based on MIT source code. Or maybe more complicated if your project is going to be under a proprietary license.
    – majinnaibu
    Apr 24 at 2:33

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