Python in the Browser
No installation needed. Run real Python code right here using Pyodide. Pick a level to start.
Level 00 — Absolute Beginner
Follow-along demos: print, variables, loops, functions. No coding challenges — just explore and experiment.
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01
First Steps
Math and print statements
Beginner
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02
Hello World
Your first print() calls
Beginner
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03
Your First Script
Code runs top to bottom
Beginner
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04
Variables
Store and reuse values
Beginner
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05
Numbers and Math
Arithmetic and order of operations
Beginner
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06
Strings and Text
f-strings and string methods
Beginner
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07
User Input
Interactive programs with input()
Beginner
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08
Making Decisions
if, elif, else
Beginner
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09
Lists
Ordered collections
Beginner
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10
For Loops
Iterate over items
Beginner
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11
While Loops
Repeat until condition met
Beginner
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12
Dictionaries
Key-value pairs
Beginner
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13
Functions
Reusable code blocks
Beginner
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14
Reading Files
Data from files (simulated)
Beginner
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15
Putting It Together
Complete mini-program
Beginner
Level 0 — First Real Projects
Write functions, pass tests, and solve problems. Each exercise has a Check button to validate your solution.
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1
Hello Lab
Write a greeting function
Easy
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2
Calculator
Four arithmetic operations
Easy
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3
Temperature Converter
Celsius and Fahrenheit
Easy
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4
Yes/No Questionnaire
Count responses by category
Easy
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5
Number Classifier
Even/odd, positive/negative
Easy
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6
Word Counter
Count word occurrences
Easy
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7
Password Generator
Random secure passwords
Easy
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8
String Cleaner
Normalize messy text
Easy
Level 1 — Building Confidence
Validation, parsing, and data processing. Functions return structured results.
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1
Input Validator
Validate email format
Medium
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2
Password Strength Checker
Classify weak/medium/strong
Medium
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3
Unit Price Calculator
Find the best deal
Medium
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4
Log Line Parser
Extract structured data from logs
Medium
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5
CSV Reader
Parse CSV text into dicts
Medium
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6
Gradebook Engine
Calculate averages and letter grades
Medium
Level 2 — Data Structures
Nested data, error handling, pipelines, and report generation.
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1
Dictionary Lookup
Safe lookups and search
Challenging
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2
Data Flattener
Flatten nested structures
Challenging
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3
Data Cleaning Pipeline
Strip, convert, filter records
Challenging
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4
Error-Safe Divider
Graceful error handling
Challenging
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5
Text Report Generator
Formatted text output
Challenging
Level 3 — Packages and Testing
File paths with pathlib, module systems, and writing your own tests.
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1
Path Builder with pathlib
Join paths and get extensions
Challenging
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2
Module Simulator
Create and call module namespaces
Challenging
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3
Simple Test Runner
Build a mini test framework
Challenging
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4
Path Manipulation Toolkit
Split, change ext, get parent
Challenging
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5
Package Registry
Register and search packages
Challenging
Level 4 — Data Pipelines
Schema validation, data transformation, nested extraction, and pipeline composition.
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1
Schema Validator
Validate dicts against type schemas
Challenging
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2
Data Transformer
Filter, map, sort pipelines
Challenging
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3
JSON Parser
Extract nested data with dot paths
Challenging
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4
Data Pipeline Builder
Compose load, clean, transform steps
Challenging
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5
Schema Builder
Infer and validate data schemas
Challenging
Level 5 — Resilience Patterns
Retry logic, circuit breakers, scheduling, backoff, and fault-tolerant processing.
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1
Retry with Counter
Retry failing functions N times
Challenging
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2
Circuit Breaker
Stop calling failing services
Challenging
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3
Priority Task Scheduler
Schedule tasks by priority
Challenging
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4
Exponential Backoff
Calculate retry delay timings
Challenging
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5
Fault-Tolerant Processor
Process batches with fallbacks
Challenging
Note: These browser exercises use
Pyodide to run real Python in your browser.
For the full experience (file I/O, pytest, linting), install Python locally using the
Setup Guide.
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