The encoder reads all source tokens and produces hidden states e0…eN.
At each decoder step, attention scores each encoder state: score(d_t, e_i) = d_t · e_i
Weights = softmax(scores). The context vector is a weighted sum of encoder states.
This lets the decoder "look back" at any part of the input - the heatmap shows which encoder tokens each decoder step attends to.
Seq2Seq with Attention - Interactive Visualization
Seq2seq models encode an entire input sequence into a fixed-length context vector, then decode it into an output sequence. Attention solves the bottleneck problem: instead of compressing everything into one vector, the decoder learns to attend to different encoder positions at each step. The attention weight matrix is a soft alignment between input and output tokens - directly interpretable as 'what input is the model looking at right now'.
Watch the encoder process input tokens and build up hidden state representations at each position
See the context vector bottleneck: without attention, all information must pass through a single fixed-size vector
Observe the attention heatmap: bright cells show which input positions receive focus during each output step
Understand additive (Bahdanau) vs multiplicative (Luong) attention - different scoring functions for the same idea
See how attention was the critical insight that led directly to the Transformer architecture two years later
Part of the EngineersOfAI Interactive 3D - free interactive visualizations covering every major concept in machine learning and AI engineering. Hover any element for a plain-English explanation. No code required.