Modify sources under Apache License 2.0

Question

Say I am working on some application in my free time, with non-commercial purposes.

Surfing around I find some sources from some developer that has created a parser for the type of data I am also working on. But his parser is way better than mine. I would like to copy it into my project, and modify it to suit my needs.

It is licensed under the Apache License 2.0. I am planning to license my project under the same license.

Can I use and modify his sources? If so, how should the copyright header look like now?

It used to be:

Copyright (C) 2008 Joe Doe

Should it now be something like this?

Copyright (C) 2009 Joe Doe for original sources and Myself for some modifications

I am guessing this is a common question among developers starting out in the open source world. And I can't get a clear answer anywhere.

Now a follow-up question? Does anything change if I were to turn my application into a closed-source, commercial one?

Answer 1

IANAL.

You should leave Joe Doe's copyright notice intact (unchanged) You can add your own too. Hence:

Copyright (C) 2008 Joe Doe
Copyright (C) 2008 E Spinchi

You might add a note about which bits were modified by you. You might note the base version of Joe Doe's work that yours is based on.

Check the terms of the Apache License 2.0; that's the normal technique for any code, open or closed, and is explicitly required by the Apache License 2.0.

If you were to turn your code into closed-source commercial code, then you still have to respect the Apache License 2.0 in full. That seems to mean you must make the original code available to those who ask for it. My casual reading does not indicate that everything must also be licenced under the same licence - but don't take my word for it (go to a real lawyer).

Answer 2

To my knowledge, the Apache license does not require that derivative works be based on that license. So the software can be turned into closed source.

See the following references:

• "Apache License requires preservation of the copyright notice and disclaimer, but it is not a copyleft license — it allows use of the source code for the development of proprietary software as well as free and open source software."

  en.wikipedia.org/wiki/Apache_License

• "permits code that it covers to be subsumed into closed source projects"

  http://www.oss-watch.ac.uk/resources/apache2.xml