$ whoami
A coding adventure built around actual Python.
No cartoon blocks, no simulated code. Real Python, real programs, wrapped in fun story problems that make it click — for kids in grades 1–10.
445+ free problems · nothing to install · no email required
1🔒name = input()23🔒# Beep wants to say hello!4print(f"Hello, {name}! I am Beep!")
🎉 All 2 tests passed!
$ cat why_leetkid.md
Built to actually teach, not just entertain.
Actual Python. Not blocks.
Every problem is a real .py file running real CPython in the browser (via Pyodide). What they write here is the exact same language used at every tech company on Earth.
Given code is locked
Input parsing and output lines a problem gives you are visible but uneditable — so passing a test means actually solving it, not just rearranging what gets printed.
1🔒alex_backpack = int(input())2🔒robin_backpack = int(input())34🔒# Swap the two so they trade weights5alex_backpack = robin_backpack6robin_backpack = bag7🔒print(alex_backpack)8🔒print(robin_backpack)
See the 🔒 lines above? Those are given — the input and the print statements can't be edited. They have to write the actual swap logic themselves to pass, every time.
Here they forgot to save alex_backpack's original value before overwriting it — a real mistake, caught the same way it would be in any Python editor: an underlined line, an error icon in the gutter, and the real traceback below.
Python said:
NameError: name 'bag' is not defined
💡 tip
Python doesn't recognize a name you used — maybe a variable that isn't spelled the same way everywhere, or hasn't been created yet.
Real errors, always — plus a plain-language tip underneath, so the traceback teaches instead of just confusing.
$ ls curriculum/
A real learning path, 445+ problems deep.
Free to browse every problem, story, and hint. Writing and running code — and saving progress — takes a free account.
Python Basics
Your journey begins here — the building blocks every Python program is made of, taught one small idea at a time.
Intro to Python
Your very first coding adventure! Meet Python, learn how to talk to the computer, and write your first working programs.
Puzzle Workshop: Explorer
Your problem-solving adventure begins! Friendly puzzles that turn your Python skills into real solving power — searching, sorting, stacks, queues, and your first famous challenges.
Puzzle Workshop: Adventurer
The training wheels come off. Trickier searches, hand-built sorts, bracket inspectors, hot-potato circles, and simulations — the puzzles that make you a real problem solver.
Puzzle Workshop: Champion
The summit. Binary search mastery, greedy strategies, two-pointer tricks, and the famous interview classics — ending at the Final Door. Solve these and you've truly graduated.