Labs
Learn by doing, not just reading
Interactive playgrounds for the concepts you're learning — visualize algorithms, run real SQL and code, practice regex and flexbox, and explore git and the command line. Everything runs 100% in your browser: nothing is uploaded and nothing is logged.
Sorting Visualizer
Watch bubble, insertion, merge, and quick sort run step by step.
Pathfinding Visualizer
Draw walls and watch BFS, DFS, Dijkstra, and A* find the path.
Data Structure Playground
Push, pop, insert, and search live stacks, queues, and BSTs.
SQL Playground
Run real SQL against an in-browser database — no setup, no server.
Regex Lab
Solve graded regex puzzles — match the right strings, skip the rest.
Flexbox Game
Master CSS flexbox by guiding items onto their targets.
Git Sandbox
Commit, branch, and merge on a live visual commit graph.
Code Playground
Write and run JavaScript or Python live in your browser.
Linux Terminal
Practice shell commands in a safe simulated filesystem.
API Playground
Send real HTTP requests and inspect the response, live.
Interactive coding labs
Labs are hands-on companions to our learning tracks. Instead of only reading about how quicksort or Dijkstra's algorithm works, you watch it run step by step; instead of memorizing SQL syntax, you run real queries against a live database; instead of guessing at a regular expression, you solve graded puzzles until it clicks.
Every lab runs entirely in your browser — the SQL engine, the Python runtime, the filesystem, and the visualizers are all client-side. Nothing you type is uploaded to a server, so it stays fast, private, and works offline once loaded.
Pair the labs with our roadmaps, learning tracks, and cheatsheets to turn theory into intuition.