What's the best Android app for identifying a bird just by its song?

Merlin Bird ID by Cornell Lab is widely considered the premier tool for identifying birds by sound. The app's standout feature is Sound ID, which uses the device's microphone to listen to the surrounding environment. As birds vocalize, the app displays their names in real-time, with waveforms that light up to indicate which species is currently calling. This is particularly valuable in dense forests or low-light conditions where visual identification is difficult. For bird survey work or casual walks, this feature transforms a smartphone into a powerful field assistant.

The app is completely free, with no subscriptions or paywalls, which reviewers consistently highlight as a major advantage. It includes extensive regional bird packs for offline use, though some users note that the ability to log sightings without any data connection could be improved. While the Step-by-Step ID feature is better for broad narrowing, Sound ID is the technical marvel here, built on decades of ornithological research. Reviews indicate it has successfully introduced many people to birdwatching, significantly deepening their engagement with nature by making bird songs decipherable.