The Public Library of Science (PLOS), The Scholarly Publishing and Academic Resources Coalition (SPARC), and the Open Access Scholarly Publishers Association (OASPA) developed the "HowOpenIsIt?®" Open Access Spectrum (OAS) guide; see https://www.plos.org/how-open-is-it. The figure below shows where Cochrane Reviews fit onto this open-access spectrum for gold* and green open access (updated March 2016). The categorization is the same for Cochrane protocols, except that from February 2016, protocols are free to view upon publication as part of the green open access policy.
Machine readability is one of the core components included in the guide. Contact Deborah Pentesco-Murphy (firstname.lastname@example.org; Publisher, Wiley) to discuss permission to crawl or access the article full-text, metadata, and citations, and the use of an API for this purpose.
*Note: The gold open access categorizations would change if published with a CC BY licence.