The Illustrated Transformer

by Jay Alammar

IntermediateGuideFree~45 min read

The illustrated explainer that made the transformer architecture click for a generation of engineers.

Start LearningReviewed July 3, 2026

Overview

Before you read 'Attention Is All You Need,' read this. The Illustrated Transformer breaks the architecture into clear, annotated diagrams: how self-attention computes queries, keys, and values; why multi-head attention helps; and how the pieces stack into an encoder-decoder. It's the single most recommended conceptual explainer of the architecture underlying every modern LLM, and it's free.

At a Glance

Topic
Models
Level
Intermediate
Format
Guide
Cost
Free
Duration
~45 min read
Provider
Jay Alammar
Hands-on
No
Certificate
None

What You’ll Learn

  • How self-attention works, step by step
  • Multi-head attention and positional encoding
  • Encoder/decoder structure of a transformer
  • The intuition behind the architecture

Highlights

  • The canonical visual transformer explainer
  • Diagram-driven and beginner-friendly

Who It’s For

Best For

  • Anyone who wants to understand transformers conceptually

Prerequisites

  • Basic neural network familiarity

FAQ

What is The Illustrated Transformer?

Jay Alammar's famous visual walkthrough of the transformer architecture — self-attention, multi-head attention, and encoder/decoder stacks.

Is The Illustrated Transformer free?

The Illustrated Transformer is free to access.

What level is The Illustrated Transformer for?

The Illustrated Transformer is aimed at a intermediate audience. Recommended background: Basic neural network familiarity.

How long does The Illustrated Transformer take?

Expect roughly ~45 min read. Most learners work through it at their own pace.

What will I learn from The Illustrated Transformer?

You'll learn: How self-attention works, step by step; Multi-head attention and positional encoding; Encoder/decoder structure of a transformer; The intuition behind the architecture.

Topics

transformerattentionarchitectureexplainer