Khan Academy

Khan Academy's computer science curriculum is completely free and teaches programming through Python, JavaScript, HTML, CSS, and data structures with no paywalls or ads. Each topic breaks into short videos paired with interactive exercises where you code directly in the browser to practice. The explanations are methodical and visual, designed to help you understand the "why" behind each concept.

Start here if you're new to programming, can't afford paid platforms, or want a thorough foundation in computer science basics. Khan Academy excels at clarity and depth for beginners rather than breadth for rapid progress; what you learn here sticks because the pacing lets concepts settle in.