Programming Languages
Programming languages from Bash and C through Swift, TypeScript, and Rust, each with step-by-step replay.
Egtry
Free interactive lessons that run and show every step. Watch real programs execute line by line in 19 programming languages, then follow 14 tracks from algorithms and data structures to physics and machine learning.
Watch code run
Examples from the lessons play one after another. Press Step to take control.Tracks
Pick a subject to see the lessons and step-by-step diagrams available for that track.
Data Structures and Algorithms
Core structures, algorithms, graph traversals, and replayed execution steps.
Web
HTML, CSS, SVG, Canvas, WebGL, and browser-side data handling.
Python Data Analysis
Data preparation, grouping, visualization, and analysis workflows.
Mathematics
Arithmetic through calculus, linear algebra, statistics, and geometry.
Applied Math
Computing, graphics, signals, control, optimization, and numerical methods.
Physics
Classical mechanics, energy, waves, circuits, relativity, and quantum topics.
Biology
Molecular biology, genetics, population models, and bioinformatics diagrams.
Finance
Pricing, risk, portfolio ideas, and market mechanics with traceable calculations.
Law
Rule models and procedural flows expressed as classroom-friendly diagrams.
Databases
Query plans, isolation, storage, indexing, and transaction behavior.
Operations Research / Optimization
Flow, assignment, scheduling, dynamic programming, and search methods.
Networks & Encryption
Packets, protocols, routing, keys, and encryption steps you can check.
Machine Learning
Model training, gradients, trees, clustering, and evaluation by traced data.
Lessons
More than 2,200 free programming lessons, plus lessons in the other tracks. Every example runs and shows each step.