Building a Transformer From Scratch in Annotated PyTorch

This guide rebuilds the original “Attention Is All You Need” Transformer from scratch in PyTorch—no high-level APIs. It covers encoder-decoder architecture, multi-head attention, masking, positional encoding, teacher forcing, and the Noam scheduler. You’ll train on a synthetic reversal task and visualize attention maps to truly understand how Transformers work under the hood.