Converting gene names from one public database format to another
I tend to use Ensembl Biomart for such queries since there are APIs for various programming languages, e.g. biomaRt, and, maybe more interestingly, via a REST API (although it’s a pretty terrible one).

To translate identifiers from different databases, proceed as follows:


Choose database “Ensembl genes”
Choose dataset your desired oganism
Go on “Filters” › “Gene:” › “Input external reference ID list”


Select the chosen source database
Provide a list of IDs, delimited by newline

Go to “Attributes” › “Gene:” › untick “Transcript stable ID”


If Ensembl IDs are desired, leave “Gene stable ID” ticked …
Otherwise untick it; go to “External:”, tick your desired identifier format

Click “Results” at the top left. This gives a preview that can be exported into various formats; alternatively the top centre buttons “XML” and “Perl” provide the query in XML (for SOAP/REST requests) and as a (horrendously formatted) executable Perl script.