Factors mentioned below are considered while optimizing apk:
1. APK Analyzer tool
2. Reduce Resource Count and Size
3. Remove Unused Resources
4. Add “shrinkResources = true” in build.gradle file.
5. Minimize Resource Use from Libraries
6. Support Only Specific Densities
7. Reduce Animation Frames
8. Crunch PNG Files
9. Remove Unnecessary Generated Code

As explained in tutorial use site below for .png or .jpg compression:
https://tinypng.com/

Download TNews app on Play Store:
https://play.google.com/store/apps/details?id=com.nikshit.tnews

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