Learn Prompting (learnprompting.org) is the world's largest free, open-source course and resource hub for prompt engineering and effective AI communication in 2026. It offers beginner-to-advanced guides, structured courses (e.g., ChatGPT for Everyone, Advanced Prompt Engineering), research-backed techniques, and specialized masterclasses on AI security/red-teaming. With 3M+ learners, multilingual support, a massive Discord community, and free core content (paid on-demand/live options), it's the go-to platform for mastering LLMs like ChatGPT, Claude, and Gemini.

fast.ai is a leading non-profit platform in 2026 for democratizing deep learning, offering free practical courses like Practical Deep Learning for Coders, the fastai PyTorch library, and tools such as nbdev. It emphasizes top-down, code-first learning for real-world applications, with community support and updates including Stable Diffusion implementations. Ideal for coders wanting hands-on deep learning skills without heavy math prerequisites—completely free with strong focus on accessibility and ethics.