See the README files of the individual subprojects:

• The main implementation of flutter_dropzone.
• The platform interface of flutter_dropzone.
• The web implementation of flutter_dropzone.

Breaking changes

3.0.x is compatible with Flutter 2.5 (stable) and later. If you're not yet ready to upgrade from a previous version of Flutter, stay with the latest 2.0.x version of flutter_dropzone. See the README of the web implementation for details.