Proofrun: Learn Python & SQL

Learn to code in the age of AI: read, run and fix the code AI writes.

AI assistants can write code for you. Knowing whether that code is right is the skill that matters now. Proofrun teaches Python, SQL, JavaScript and HTML/CSS through short daily lessons. You run real code on your phone, offline, with no account.

HOW YOU LEARN
• Predict the output: read a snippet and say what it prints before you run it.
• Spot the AI bug: find the mistake in code an AI assistant wrote.
• Prompt drill: write the request that gets you the code you need, then check the result.
• Make it pass: edit the code until every check turns green.

REAL CODE ON YOUR PHONE
• Real runtimes built into the app for Python, JavaScript, Node.js, React, HTML/CSS, SQL, PHP, C, C++ and Java.
• Lessons and the playground work offline. Every run shows how many milliseconds it took.
• Errors explained in plain English: which line broke and why.
• SQL practice on real tables: write a query and see the result grid.

REAL-WORLD SKILLS
16 tracks and 472 lessons. Next to Python, SQL, JavaScript and HTML/CSS, there are tracks for the work people do with code today:
• Generative AI: write the code around AI models: prompts, structured JSON output, tool calls and search over your own documents.
• APIs & JSON: call web APIs, read JSON and handle errors and retries.
• Data analysis with pandas: load, clean, group and join real tables.
• Machine learning with scikit-learn: train regression and classification models and measure them honestly.
• Automate with Python: rename and sort files, pull data out of text and merge spreadsheets.
• Coding interview in Python: the problem types interviews use, solved and explained, with Big-O.

SEE WHAT YOU'LL BUILD
Open the showcase to see finished pages and projects made in Proofrun, live on your phone. 92 step-by-step projects take you to the same result.

SHARE → RUN
Copied code from ChatGPT or Claude? Share it to Proofrun and run it in one tap to see what it really does.

A HABIT YOU KEEP
A daily goal, streaks, streak freezes and a review queue that brings back what you got wrong.

AI TUTOR
Stuck? Ask for a hint or have an error explained. The AI tutor is for users aged 18+, needs an internet connection and can make mistakes.

FREE AND PRO
The first 5 lessons of every track and the playground are free. The free version shows ads. Proofrun Pro unlocks every lesson, the AI tutor, certificates and the C/C++ pack, and removes ads.
Pro is an auto-renewing subscription, monthly or annual. The annual plan starts with a 7-day free trial for eligible new subscribers. Payment is charged to your Google Play account at confirmation. The subscription renews unless you cancel at least 24 hours before the period ends. Cancel anytime in Google Play under Payments & subscriptions.

Privacy Policy: https://cosmovex.web.app/apps/coderun/privacy-policy
Terms of Use: https://cosmovex.web.app/apps/coderun/terms

Recent changes:
New: a live AI tutor that helps the moment you're stuck.
• Explain it another way, or ask anything about a lesson
• An AI hint once the written hints run out
• After you pass: explain my solution, test it and review my code
• Run tab: describe what you want and AI writes the code for you to run and check
1 AI credit per answer. You start with free credits, Pro includes 10 every month, and you can buy more. Saved offline explanations stay unlimited.