Practice tools for Python, SQL and Linux
Three browser tools for running the code you just read about. Nothing to install, and nothing left behind on your machine.
🐍 PyChallenge: Python exercises in the browser
Reading a tutorial and understanding it are two different things. PyChallenge has graded exercises across most of the language, covering variables, strings, lists, dictionaries, loops, functions, classes, files, Flask, Pandas and Matplotlib. You type an answer, it runs, and if you are wrong it tells you why.
Good for: beginners who want feedback while the syntax is still fresh, and anyone who wants to check one specific idea without setting up a project first.
Not for: third party packages, or anything that needs a running server.
🗄️ SQLCrab: run the query before you ship it
Most database bugs are obvious the moment you look at the query. SQLCrab is an SQL editor in the browser with preloaded sample tables. Write a SELECT, a JOIN or a window function, run it, and see the actual rows. No connection string, no driver to install, no OperationalError.
Good for: checking joins, aggregations and date handling before they reach sqlite3, psycopg2 or SQLAlchemy.
Not for: migrating a production schema. It is a scratchpad, not a database server.
🐧 PracticeLinux: a real terminal on a throwaway machine
Most of the friction in a Python tutorial is not Python. It is sudo apt-get install, a service that will not start, a port that is already in use, a virtualenv in the wrong directory. PracticeLinux gives you a disposable Linux terminal in the browser, so you can install, start, stop, kill and reset as often as you like without changing anything on your own computer.
Good for: the setup half of a tutorial, covering database servers, Flask and Django deployment, Selenium drivers, pip and virtualenv.
Not for: long lived work. It resets.
❓ Common questions
Can I practise Python online without installing anything?
Yes. PyChallenge runs graded Python exercises in the browser. You open an exercise, type the answer and get told what is wrong with it, with no interpreter, virtualenv or package install on your own machine.
Where can I run SQL queries without setting up a database?
SQLCrab. You write a query against sample tables and see the result set immediately, which is the quickest way to check a join or a GROUP BY before it reaches your Python script. The SQLite, PostgreSQL and SQLAlchemy tutorials cover the Python side.
Can I try Linux commands without installing anything on my computer?
Yes. PracticeLinux is a disposable Linux terminal in the browser. Install packages, start services, kill a stuck server and reset the environment as often as you like, and nothing persists on your machine. It pairs well with the subprocess and Python IDE tutorials.
🧭 Which tool goes with which tutorial?
- Python introduction — set up python3 and pip in a sandbox first
- Loops, strings, dictionaries — graded exercises after each one
- Classes and OOP — exercises for attributes, inheritance and methods
- SQLite, PostgreSQL, MySQL — test the query, then install the server in a sandbox
- SQLAlchemy ORM — check the generated SQL in the SQL editor
- Subprocess, modules, IDEs — run the install and terminal commands in a sandbox
- Flask, Django — build the server environment in a sandbox
- Selenium — match the driver and browser versions in a clean terminal
- Pandas, Matplotlib — exercises with the expected result next to yours