Could you list healthy, unsweetened coffee flavouring syrups? Most of the coffee syrups sold by big chain cafes are either traditionally sweetened or artificially sweetened.  However, the flavoured coffee they have "on tap" are completely unsweetened, which is what I seek.  I've done some initial web scouting for syrups, but it's not always easy to ferrut out a complete ingredients list.  Though I have come across lists such as "other ingredients" below the nutrition table.  Not too sure how to interpret that, as I do not view the nutritional table as an ingredients list at all.  Many syrups are general-purpose rather than being meant for coffee.

Rather than continue running down what seems like a high ratio of information dead ends, I'm hoping to leverage the awareness of those who already enjoy healthy coffee flavouring syrups that are completely unsweetened.  Even slightly sweetened would be fine, as long as it doesn't consist of recently developed     alternative sweeteners, even of the all-natural variety (I want to avoid accusations of slagging products by mentioning names).  If you are able to divulge what your syrup is, I'd appreciate it.  If you can provide the ingredients and/or nutritional info, either as text, photos, or URLs, so much the better.

From my attempts to inquire about suitable syrups in decades past, I suspect and hope that there are few candidate options that (i) are targeted to coffee; (ii) are completely (or almost completely) unsweetened; and (iii) have their ingredients (and maybe the nutrition) list available online.  If so, then this question is not nearly as open-ended as it may seem at first glance.
The brand MiniSyrup seems to meet your requirements. From their website,


  SUGAR/SWEETENER/CALORIE FREE. Unlike the big bottles of syrup that are crammed with sugar or artificial sweeteners like sucralose and aspartame, MiniSyrup Flavor Shots are the first completely unsweetened flavoring made to flavor your favorite beverages like brewed coffee, hot chocolate, lattes, fountain sodas, tea and more. This gives you complete control over not only the flavor in your beverage, but also your sweetness. [1]


They don't seem to have nutrition information on their website, but myfitnesspal lists the nutrition information for some of their flavors. I'm not sure of the validity, but as you mentioned in a comment you can reach out to MiniSyrup for more information.