A real playground, right on your page.
Code Runner is a tiny code playground you can embed anywhere in Notion. Pick a runtime language, type a few lines, and press Run (or Ctrl/Cmd+Enter) — the output console shows exactly what your program printed, including errors.
JavaScript executes instantly and 100% locally inside a sandboxed iframe — no network needed. The other 22 languages (Python, TypeScript, Java, C, C++, C#, Go, Rust, PHP, Ruby, Swift, Kotlin, Bash, Lua, Dart, Scala, Perl, Haskell, Elixir, R, SQL, Assembly) run through the free Judge0 CE API. Your code is saved per language, so your Python scratchpad survives a page reload.
Pick HTML or CSS and the output console turns into a live preview pane: your markup renders exactly as a browser would draw it, and CSS is applied to a small demo page (heading, paragraph, button, boxes, list) so you can see selectors, the box model, flexbox and colors take effect instantly — offline, with no API call.
⚙️ Settings & Customization
- Theme
- Language
- Size
- Transparent background
- 🎨 Accent Color
Changes apply live — the embed link on the right and the preview above update instantly.
📖 How to embed in Notion
- Copy the embed link from the sidebar on the right.
- Open the Notion page you want the widget on and type
/embed. - Paste the link into the embed dialog and press
Embed link. - Drag the embed's bottom edge to resize it to taste.
- ✦ 25 languages — JavaScript, HTML and CSS run fully offline
- ✦ New: HTML and CSS render in a live preview pane
- ✦ SQL (SQLite) and Assembly (NASM) via Judge0
- ✦ Sandboxed iframe with console capture + infinite-loop watchdog
- ✦ Code persists per language across reloads
- ✦ Ctrl/Cmd+Enter to run, Tab indents
- ✦ 21 UI languages with RTL support