The FilledStacks framework provides a number of tools and widgets to build Flutter apps.
I’ve only used the state management and routing system although I took a look at the testing framework and it actually looks useful compared to many other testing frameworks I’ve seen.
Some users have complained that it is difficult to learn but I’d have to disagree, I found it simple and the tutorials helpful. While it’s not the ideal way I’d build apps I do have to say it’s pretty close and any flaws can be overlooked given the overall package offerings.
Whether it is any good or not depends on your preferences and needs. You can check out their website and documentation for more details.