What is an Opinionated Framework?

An Opinionated Framework is a Web Development Framework that makes a lot of the decisions for you.

If you use an opinionated framework, then you generally have to do things the way the framework intended for you to do them.

For example, Rails is a highly opinionated framework:
Your models go in the app/models folder, your configuration goes in the config
folder and your routes go in routes.rb.

One of the main benefits of an opinionated framework is consistency. Any Rails developer can quickly work on another Rails project.

Opinionated frameworks can also save you time. You don't have to waste time making trivial decisions and reinventing the wheel.

And one of the main drawbacks is that whenever you need to do something that isn't supported by the Framework, it can be unnecessarily difficult.

For example, before Rails 6.0 you had to jump through a lot of hoops if you wanted to use multiple databases in your application.

The best Opinionated Frameworks provide an "escape hatch" which will effectively turn off the framework and let you build whatever you need to build.

An example of an un-opinionated framework is ExpressJS. Its motto is "Fast,
unopinionated, minimalist web framework for Node.js". With Express, you have to decide how to organize your code and which packages you to use.

Many developers like unopinionated frameworks because they have their own opinions! They want a framework that doesn't impede their ability to make the choices they want to make.