(3Z)-3-Hydrazinylideneindolin-2-one

The title mol­ecule, C(8)H(7)N(3)O, is almost planar, with a maximum deviation of 0.0232 (2) Å from the least-squares plane. The Z conformation of the C=N double bond is stabilized by an intra­molecular N—H⋯O hydrogen bond. In the crystal, adjacent mol­ecules are linked by inter­molecular N—H⋯N and N—H⋯O hydrogen bonds, forming zigzag sheets parallel to the c axis; the sheets are further stabilized by π–π inter­actions [centroid–centroid distance = 3.7390 (10) Å].