When you snap blocks together in CryptoBlocks, you’re not writing JavaScript. You’re not writing Python either. You’re building logic. The language comes after.

Every single block in CryptoBlocks has two implementations — one in JavaScript, one in Python. When you hit Run, the system generates code in whichever language you’ve selected and executes it right in your browser.

How It Works Under the Hood

Each block definition includes both a JavaScript and Python implementation. They do the same thing, but in the syntax of each language. A “reverse text” block calls text.split('').reverse().join('') in JavaScript and text[::-1] in Python. Same result. Different spelling.

JavaScript runs in a sandboxed iframe. Python runs through Pyodide — a full CPython interpreter compiled to WebAssembly. Both execute entirely in your browser. No servers involved.

Why Two Languages?

Because the world doesn’t run on one language.

JavaScript powers every website you’ve ever used. Python powers data science, AI, and automation. If you want to build things that matter, you’ll want both in your toolbox eventually.

Learning two languages at the same time sounds hard. It’s actually easier when you can see them side by side. Build a program with blocks, peek at the JavaScript, switch to Python, and compare. You’ll notice that the concepts are identical — loops, variables, functions, conditionals. Only the punctuation changes.

Async Built In

Some blocks do things that take time — like waiting or fetching data. CryptoBlocks detects when a block’s implementation is async and automatically wraps the generated code with await. You don’t need to think about promises or async/await syntax. The blocks handle it.

Live Output Streaming

Both languages stream output to the screen in real time. If your program prints five things inside a loop, you see them appear one by one, not all at once when the program finishes. This makes debugging way more intuitive — you can see exactly where your program is and what it’s doing.

Two languages. One set of blocks. Zero excuses not to learn both.