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Lets you build your own design pattern unlike other frameworks with already MVC pattern built-in. Easy to learn and thanks to clear documentation. One big plus for me is the easy to learn ORM feature that supports sql, and nosql. I can no longer worry about using both db or switching from one to another bec my orm code will be the same; just change db settings.
SpecsUpdate
Pros
Pro No canned coding/directory structure
Freedom to structure your projects' directories and codes as you wish.
F3 is a non-opinionated framework : you are entirely free to use the files/API/assets structure that you love.
Following a minimalistic approach, F3 tends to avoid adding code and structure that are not strictly necessary, while focusing on what really matters : coding your solution; actually you learn F3 while implementing/coding your project/webapp
Pro Vibrant community behind the framework
The community is responsive and helpful in clarifying the aspects of the framework.
Pro Comprehensive documentation and API reference
Concise and to the point documentation. Includes many examples and complete API reference.
Cons
Con Backward incompatible within minor version
There are serious incompatibilities even between minor versions (eg. between 3.6.0 and 3.6.2). Developers exhibit complete lack of understanding what is versioning of product (and which changes should be integrated in which versions), which makes this framework unsuitable for serious work. Development is slow, stable versions are rare and not treated seriously.
Con Default ORM doesn't support joins
The default ORM for this framework is missing some features such as joins. But it's important to keep in mind that it's a small plugin, only 23KB in size which still can be replaced with a larger ORM if needed.
An alternative the drop in f3-cortex ORM which is popular, and supported by the community, which supports Joins and much more.
Con Need more example of working code and directory structures and usage with JS and CSS frameworks
Con Lack of video tutorials
While there is a great user guide, compared to other established PHP frameworks, there is a relative shortage of video and written step-by-step tutorials for newbies to learn this framework.
Recommendations
Comments
Flagged Pros + Cons
Con Requires front-end stack support
As often used with a .js framework or libraries there is a need for a combined workflow. For example, a workflow using laraval-mix+ nom.