Minify android app but do not obfuscate it

Question

minifyEnabled true

is just a shortcut for:

postprocessing {
    removeUnusedCode true
    obfuscate true
    optimizeCode true
}

So, if you want to minify without obfuscating, replace minifyEnabled true with:

postprocessing {
    removeUnusedCode true
    obfuscate false // <--
    optimizeCode true
}

Additionally, the compiler will complain if you have shrinkResources true. The equivalent postprocessing field is removeUnusedResources true, i.e:

postprocessing {
    removeUnusedCode true
    removeUnusedResources true // <--
    obfuscate false
    optimizeCode true
}

Contrary to other answers, useProguard false does not disable obfuscation; it changes the obfuscation engine from ProGuard to R8.

Yes, you can use ProGuard to minify debug builds.

The key is to use -dontobfuscate option in ProGuard configuration for debug build.

Use this setting in build.gradle:

buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 
            'proguard-rules.pro'
    }
    debug {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 
            'proguard-rules.pro', 
            'proguard-rules-debug.pro'
    }
}

Write your release ProGuard configuration to proguard-rules.pro.

Use the same configuration for release and debug. This way you ensure that no necessary code is stripped away. And debug minification doesn't break the build.

Add extra ProGuard config file proguard-rules-debug.pro for debug build. It should contain rules used only for debug. In this case add only:

-dontobfuscate

Tomik's answer is technically correct, but it doesn't support using Instant Run for your builds. As pointed out in the official guide on code-shrinking:

Enable code shrinking with Instant Run If code shrinking is important to you while incrementally building your app, try the experimental code shrinker that's built into the Android plugin for Gradle. This shrinker supports Instant Run, unlike ProGuard.

You can configure the Android plugin shrinker using the same configuration files as ProGuard. However, the Android plugin shrinker does not obfuscate or optimize your code—it only removes unused code. So you should use it for your debug builds only, and enable ProGuard for your release builds so your release APK's code is obfuscated and optimized.

So the proper solution would be to setup your debug build like this:

android {
    buildTypes {
        debug {
            minifyEnabled true
            useProguard false
            proguardFiles getDefaultProguardFile('proguard-android.txt'),
                    'proguard-rules.pro'
        }
}

This way the code in your debug build doesn't get optimized nor obfuscated, but will get shrunk. This also applies when using Instant Run.

A simple solution is to add minifyEnabled true and useProguard false inside the build configuration. But code shrinking is not recommended for debug builds from official docs Be aware that code shrinking slows down the build time, so you should avoid using it on your debug build if possible. Reference https://developer.android.com/studio/build/shrink-code.html