You also can build a simple recommender based on categorization of articles. XPLR (https://www.xplr.com https://www.xplr.com) for whom I work, has an API that

You also can build a simple recommender based on categorization of articles. XPLR (https://www.xplr.com https://www.xplr.com) for whom I work, has an API that among other things, allows to easily tag articles and build recommenders. If you're interested we'd be happy to let you use the API. Contact us or pm me for an access to the beta.