At this point in time, almost all new PHP code bases are being built on top of a framework, most commonly Laravel, for software applications or WordPress for website CMS platforms. However, there are still many code bases around the web that are built in raw/vanilla PHP, meaning no framework is being used. The common reasons for this include:
The code base was initially built before the rise of popular PHP frameworks in the early 2010s.
The company created its own framework or used a collection of packages.
Some developers prefer to build in a language without a framework because it’s what they know best.
Due to the advancements in frameworks like Laravel and Symfony, it’s not advised to build software in raw PHP anymore, because it will require significantly more time to build the same features vs using a framework.