Hantzsch-Widman nomenclature of over 600 heterocyclic ring systems, covering 3 to 8 membered monocyclic rings, as well as many fused bicyclic and tricyclic heterocycles. It is the modern systematic naming of heterocycles approved by the IUPAC.

The HantzWid app provides easy identification of all common (and many uncommon) heterocycles by either structure or name search. It is indispensable for both experienced and budding organic chemists interested in heterocyclic chemistry.

It is also a handy tool when working with chemical / pharmaceutical patents since the knowledge of heterocycle nomenclature is paramount.

Features included:
- Instructions to Hantzsch-Widman nomenclature
- Structure search
- Name search
- Ring atom numbering
- Links to internet searches
- Trivial names included (when appropriate)
- Examples of heterocycle (when appropriate)