I want to make an open-source graph thing which looks and behaves very similarly to Google Visualization API, but it would be based on Flot. Is this legal, or must I not imitate Google Visualization API?
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GNU has a long history of making work alikes for libraries. When BSD was sued for copyright it was over implementation copying and not interface copying (reimplementing the Unix interface was considered a valid resolution). Then as whatsisname points out in the comments Oracle lost when they sued Google for API copyright. Work alikes have a long history of being legal. So it should be ok. Though as always I am not a lawyer and this is not legal advice.
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