We'd like to use Tags to organize our contacts.
Does the v3 API have an endpoint to manage tags?
Does the v3 API support applying tags to contacts when doing a PUT to /v3/contacts/ or a POST to /v3/activities/contacts_json_import/?
I found this post which suggests tagging may be included in the v3 API. Can I get an update on the status of this development?
While there are no current plans to retire the Tags feature, our Contacts team doesn't have immediate plans for any new development involving it at this time in favor of our Segmentation feature. Our v3 API does have advanced Custom Fields features, which work well with Segments allowing you to easily segment out your list and replicate the behavior of Tags.
See here for details on our Segments feature: http://knowledgebase.constantcontact.com/articles/KnowledgeBase/25205-Define-Your-Own-List-Segments
Tier II API Support Engineer