The Heinkel HD 25 was a two-seat shipboard biplane reconnaissance floatplane developed in Germany during the 1920s for production in Japan.

It was intended to provide a spotter aircraft for warships, to take off from a short ramp since shipboard catapults had not yet been developed by the Japanese.

The HD 25 was a conventional biplane with staggered wings and twin pontoon undercarriage.

A single example of a modified demilitarised version was built by Aichi as the AB-1, and three surplus Type 2 Two-seat Reconnaissance Seaplanes were converted with two seat cabins aft of the open rear cockpit, to seat three passengers, for use by the Kouchi Shimbun newspaper.

16 were built by Aichi and saw brief service aboard the cruisers of the Imperial Japanese Navy.