Major extracellular chitinase, which is essential for chitin utilization. Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Translocated across the cytoplasmic membrane via the Sec system, and across the outer membrane via the type IX secretion system (T9SS). The C-terminal region (CTD) is necessary and sufficient for secretion by the T9SS. The CTD may be cleaved during secretion. Disruption results in cells that fail to digest chitin. Western blot and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses suggest that ChiA could be proteolytically processed into two GH18 domain-containing proteins. However, it could be the result of non-specific digestion (PubMed:24363341). Belongs to the glycosyl hydrolase 18 family. Chitinase class II subfamily.