Rafael Sidi

RESTful. As complete as possible in terms of query methods and data returned. Works with all commonly-used languages (easy if RESTful and returns XML/JSON). Something like NCBI EUtils, but without the weird query key stuff. Basically, return IDs from keyword search, allow document retrieval via those IDs. - Neil Saunders

make every page available with .json extension! - Ilya Grigorik

Ones that don't cost hobby developers and startups $0.05/API call (looking askance at you, Wolfram!) - Mr. Gunn

I'm sick of RESFUL interfaces. As Richard Akermann mentioned some time ago, a proliferation of APIs at the end of the day doesn't actually help, as you have the learning curve to get over each time you want to hook up a new API. I'm slowly coming to the conclusion that sticking your data into a RDF or pseudo-RDF store and plopping a SPARQL endpoint on it is the answer. OK, so SPARQL is... more... - Ian Mulvany

Depends on the kind of application, right? RDF is good for making datasets available but you can't parse it easily with Javascript, or fetch it cross domain, hook it up to other stuff with Yahoo! Pipes, give people one line usage examples with cURL etc. etc. I reckon REST and JSON is the way to go if you want to encourage mashups. Also, no signed requests. :) In terms of content whatever is exposed via the website should be exposed via the API. - Euan

Thanks fir the mention Ian. What I said more recently in my Access 2009 presentation is we should be mindful of our objectives when assessing API vs. data-level access. API gives more control for the provider, but may limit the scope of the applications that the provider can get from developers. Raw data gives developers much more freedom, but may create management issues as implementations proliferate. - Richard Akerman from BuddyFeed

Clear licensing information would be a big plus as well. If it is tied down or limited use that really needs to be clear. Obviously I have an ulterior motive here because if its made clear then less people will probably use it :-) - Cameron Neylon