Here are 13 websites where you can learn about frontend and backend coding:

Frontend Development

FreeCodeCamp

Provides a comprehensive curriculum covering HTML, CSS, JavaScript, and more. Offers interactive coding challenges and projects.

http://www.freecodecamp.org

MDN Web Docs

Offers detailed documentation and tutorials on HTML, CSS, and JavaScript. It's an excellent resource for learning and understanding web technologies.

http://developer.mozilla.org

Codecademy

Offers interactive courses on various frontend technologies like HTML, CSS, JavaScript, and popular frameworks like React and Angular.

http://www.codecademy.com

CSS-Tricks

Provides tutorials, articles, and guides on CSS and frontend web development techniques. It covers a wide range of topics, from beginner to advanced.

http://css-tricks.com

Udemy

Offers a vast collection of frontend development courses, including HTML, CSS, JavaScript, and popular frontend frameworks.

http://www.udemy.com

W3Schools

Offers tutorials, references, and examples on HTML, CSS, JavaScript, and other web technologies. It provides hands-on exercises for practice.

http://www.w3schools.com

Backend Development

Node.js Docs

Official documentation for Node.js, a popular backend JavaScript runtime. It provides comprehensive guides and tutorials for server-side development.

http://nodejs.org

Django Documentation

Official documentation for Django, a powerful Python web framework. It offers guides and tutorials for backend web development with Django.

http://docs.djangoproject.com

Express.js Documentation

Official documentation for Express.js, a minimalistic Node.js web framework. It provides guides and examples for building backend APIs and web applications.

http://expressjs.com

Laravel Documentation

Official documentation for Laravel, a PHP web framework. It offers comprehensive guides and tutorials for backend web development.

http://laravel.com/docs

MongoDB University

Offers free online courses on MongoDB, a popular NoSQL database used in backend development. It covers database concepts and practical usage.

http://university.mongodb.com

Flask Documentation

Official documentation for Flask, a lightweight Python web framework. It provides tutorials and examples for building backend applications.

http://flask.palletsprojects.com

These websites should provide you with a solid foundation in both frontend and backend development. Remember to practice coding regularly and work on projects to reinforce your learning.