The asymmetric unit of the title compound, C4H5N7, comprises two independent but virtually superimposable mol­ecules. Each mol­ecule is planar with the dihedral angles between the five-membered rings being 2.8 (3) and 2.1 (3)°. The crystal structure is formed by an extensive network of relatively strong N—H⋯N hydrogen-bond inter­actions. Individual mol­ecules are arranged into supra­molecular zigzag chains running parallel to [001] by way of the strongest N—H⋯N inter­actions. Adjacent chains are inter­connected by rather long (D⋯A distances range from ca 3.00 to 3.03 Å) but highly directional (inter­action angles above ca 173°) hydrogen bonds forming a supra­molecular layer in the bc plane.