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Currently I'm trying to port one tool fron Java to .NET and original Java tool is licensed under Mozilla Public License v2. Shall my port have the same license or can I apply different open source license?

Most of code of the tool's was converted automatically using Java to .NET code converter.

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Have you contacted the original authors to see what they think? They may be fine with you using whatever license. – James Feb 3 '14 at 7:53
This may depend on original license. It may have a clause saying that you are required to use the same license and open-source the code. Look up the specified license here. – John T Feb 3 '14 at 7:53
Ok, I'll try to contact authors. – hazzik Feb 3 '14 at 21:51
up vote 5 down vote accepted

The Mozilla Public License v2 is clear about the licensing of modified versions: If you make modifications to a work covered by the MPL, the modified work must remain licensed under the MPL.

The difficulty is in the determination whether a ported version should be regarded as a modified version (and thus required to be licensed under the MPL) or a new work that is (loosely) based upon the original (which means you would be free to choose your license). That determination can only reliably be made by a lawyer, which I am not.

As you state that most of the translation was done by an automated process, chances are that your .NET version will be seen as a modified version of the original.

Your best options are either to stick with the Mozilla Public License, or to contact the authors/maintainers of the original and ask them if they agree to using a different license for your port.

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Well put. Since the starting point is the MPL'd code and not a 'clean room' reverse engineering or recreation of it I think the OP would have a hard time arguing otherwise... – James Snell Feb 3 '14 at 12:59

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