How to wipe Android phone before trade in or selling?

Extirpater can be used as an additional free- if you wanna wipe Android phone before trade in, and its stated purpose is to fill available free space with random data and then remove those files. Its own documentation specifically lists "before selling your device" as a use case.

However, there are two important limitations:

⚠️ It does not wipe the entire physical flash storage. The project explicitly says that Android's flash-storage architecture and partition layout prevent it from completely filling the drive.

⚠️ It carries a real hardware-risk warning. The project warns that excessive use can destroy NAND flash storage, so repeatedly running it is a bad idea.

For a modern Android phone, encryption also changes the picture: Android 10+ devices are required to use file-based encryption, and Android's encryption keys are protected separately from ordinary user data.

My recommendation:

You might consider using the Extirpater to wipe Android before trade in; However, do not run the program repeatedly, nor should you characterize it as a forensic-grade wipe that guarantees data is unrecoverable. Official Google guidelines clearly state that a factory reset thoroughly erases all data on the phone.