In the title compound, C8H11N5O, the triazepine ring displays a boat conformation. Its mean plane is inclined to the triazole ring by 22.10 (9)°. In the crystal, molecules are linked by C—H...O hydrogen bonds to form chains parallel to the b-axis direction. Inversion-related chains are linked via offset π–π interactions between the triazole rings, forming ribbons propagating in the b-axis direction. The terminal CH3 group is disordered over two sets of sites, with a refined occupancy ratio of 0.48 (6):0.52 (6).