Any user (human or machine) may decide what representation of the resource it prefers to retrieve. This is possible through content negotiation or by modifying the request URL:

- The URL http://issn.org/resource/ISSN/[ISSNnumber]/ will provide the record in an HTML human-readable format.

- The URL http://issn.org/resource/ISSN/[ISSNnumber]?format=xml will provide the bibliographic metadata encoded as RDF/XML.

- The URL http://issn.org/resource/ISSN/[ISSNnumber]?format=turtle will provide the bibliographic metadata encoded as RDF Turtle.

- The URL http://issn.org/resource/ISSN/[ISSNnumber]?format=json will provide the bibliographic metadata encoded as JSON-LD.

Content negotiation is available for subscribing and free users although the latter can only retrieve essential ISSN metadata.