In the mol-ecule of the title compound, C(10)H(9)N(3)O(2), the pyrazole ring is approximately coplanar with the amino and carboxyl groups. The phenyl group is twisted by 48.13 (3)° relative to this plane. An intra-molecular N-H⋯O hydrogen bond stabilizes the planar conformation of the mol-ecule. The mol-ecules are linked into two-dimensional sheets by two strong inter-molecular N-H⋯N and O-H⋯O hydrogen bonds. The latter forms the classic carboxylic acid dimer motif.