A cam lock for cabinets, drawers, drug cabinets, credenzas, sliding doors, lockers, mail boxes and other door type applications is compact in size, fits an existing cam lock opening and provides electronic access via a keypad or other electronic access. Using batteries, such as AAA size batteries or smaller, the lock has electronics that release a lock turn knob or handle when the correct code is entered. Preferably a set of electronic contacts is included at an accessible position on the lock housing to allow both master access and power jumping with a common manager's implement, for situations of lost codes and/or battery failure. In a particular embodiment the lock is long, narrow and low in profile so as to fit on the margin of a steel or wood file cabinet, compatible with the cam lock opening already provided. The locks, NFC-enabled, can be used in securing delivery boxes to enable delivery access, when authorized.