Over my 15 years+ as a freelance developer, I've built a whole range of websites, banners, games and even a facial recognition system. However, here's a list of my favourite tools:
GatsbyJS enables developers to create modern, secure, fast & SEO-approved websites. Great for Headless Wordpress projects!
ReactJS is a great JavaScript library which I've used on a range of applications.
Wordpress is still my favourite CMS tool for websites. It's simple and clients love it.
GraphQL is a modern and very fast method for loading data into a website. Much better and quicker than using REST in my experience!
GSAP is a brilliant JavaScript library for creating high-performance animations on the web.