majiayu000 fastai
fastai is a layered API on top of PyTorch. It popularized Transfer Learning and good defaults (One Cycle Policy).
When to Use
- Learning DL: The best course/library for beginners ("Practical Deep Learning for Coders").
- Quick Baselines: Get state-of-the-art results in 5 lines of code.
Core Concepts
Defaults
fastai chooses the best learning rate finder, optimizer (AdamW), and augmentations for you.
Layered API
You can use the high-level Learner or peel back layers to raw PyTorch.
Best Practices (2025)
Do:
- Watch the Course: Jeremy Howard's course updates annually and is world-class.
- Use
nbdev: fastai's literate programming environment is powerful.
Don't:
- Don't get stuck: If you need something very custom, drop down to PyTorch.