I am looking for a simple, reliable and free (gratis) API which will return the corresponding UK street name for a UK postcode (preferably with no registration or key required) and am wondering where I can ask a question about that.
Might this be better asked on Open Data?
I am sure that it would be off-topic on Software Recommendations, but am unsure about the main GIS site.
If it is an API to open data that you are seeking then I think the place to ask this is at the Open Data Stack Exchange.
If you are unsure whether such data is available as open data then my understanding is that the same site will be able to clarify that for you, and may even suggest options that are free but not open, if they exist.
I can see that you have now asked your question on Open Data at https://opendata.stackexchange.com/q/14146/6229 where it has been upvoted but currently is unanswered.
