For a workshop I want to give some negative examples of badly designed APIs so that groups can work out the negative parts and how to improve them, anyone has some examples?
I am not sure if its fit in the "bad design" category you look for but OpenStreetMap API has various usability problems.<p><a href="https://wiki.openstreetmap.org/wiki/API_v0.6" rel="nofollow">https://wiki.openstreetmap.org/wiki/API_v0.6</a><p>The main issue has I see it is that all API functions accepts only XML as content-type. There is no way to use JSON, which is rather standard by now. Even GET serves only XML.<p>Another issue is that the error messages for non-conform requests are not informative enough. This is emphasize in the doc ("unfortunately error messages are not consistent").<p>Finally, in my opinion, the doc do not provide simple and clear overview of the API.