Macworld:

Apple owns all the oxygen in several territories across its ecosystems, like music-library management and photo management, competing only with giants such as Amazon and Google that can offer similar features. But in the arena of podcast apps, the decentralized distribution of audio episodes has left what seems like just enough room for independent developers.

Over the years, three companies have released version after version of the most popular non-Apple podcast apps: Pocket Casts from Shiftyjelly, Supertop’s Castro, and Overcast from Marco Arment’s Overcast Radio.

Fleishman has a good overview of what are likely the three most popular podcast listening apps.