Deeper analysis in DevTools

The *-code-size-analysis_*.json file produced above can be further
analyzed in deeper detail in DevTools where a tree or a treemap view can
break down the contents of the application into the individual file level and
up to function level for the Dart AOT artifact.

This can be done by flutter pub global run devtools, selecting
Open app size tool and uploading the JSON file.

For further information on using the DevTools app size tool, see
DevTools documentation.

Reducing app size

When building a release version of your app,
consider using the --split-debug-info tag.
This tag can dramatically reduce code size.
For an example of using this tag, see
Obfuscating Dart code.

Some other things you can do to make your app smaller are:

Remove unused resources

Minimize resource imported from libraries

Compress PNG and JPEG files