Android

Add OWASP ZAP root certificate to emulated device (API < 29 required):

$ openssl x509 -inform PEM -subject_hash_old -in owasp_zap_root_ca.pem | head -1
9e86394f
$ ln -s owasp_zap_root_ca.pem 9e86394f.0
$ ~/Android/Sdk/emulator/emulator -avd S9_API_28 -writable-system
$ adb root
$ adb remount
$ adb push 9e86394f.0 /system/etc/security/cacerts
$ adb shell "chmod 644 /system/etc/security/cacerts/9e86394f.0"
$ adb reboot

Extract APK from phone:

$ adb shell pm list packages
$ adb shell pm path <package>
$ adb pull <path>

Decompile/recompile APK:

$ apktool d -r -o patched com.example.apk

$ apktool b -o com.example.patched.apk patched
$ # Some packages require aapt v2:
$ apktool b --use-aapt2 -o com.example.patched.apk patched

$ keytool -genkey -v -keystore my-release-key.keystore -alias acut3 -keyalg RSA -keysize 2048 -validity 10000
$ jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my-release-key.keystore com.example.patched.apk acut3
$ # Or Google's signer can be used to replace a signature:
$ ~/Android/Sdk/build-tools/30.0.0/apksigner sign -ks my-release-key.keystore com.example.patched.apk

Install APK on emulated device:

$ adb install <file.apk>