Pick an example, then press Ctrl/⌘ + Enter or click Run Code.
A free, lightweight, browser-based code editor and runner. Write, edit and execute code in 25+ languages — JavaScript, TypeScript, Python, Ruby, R, HTML/CSS and SQL run live via WebAssembly, with inline output, live previews and data viewers. No installation, no sign-up, and your code never leaves your browser.
JavaScript, TypeScript, Python, Ruby, R, HTML and SQL execute live via WebAssembly — output and Matplotlib/R plots appear inline.
Monaco-powered syntax highlighting, IntelliSense-style autocomplete and themes for Java, Go, Rust, C++, C#, PHP, Kotlin and more.
Instant HTML/CSS preview and a Markdown preview that re-render as you type.
Explore JSON, XML, TOML and YAML as an interactive, searchable, collapsible tree.
Run real SQL against an in-browser SQLite database that survives reloads (saved to your browser via OPFS).
Everything runs client-side — no code is uploaded, no account, no server-side execution.
Test an idea, a regex, an algorithm or an API shape instantly — no project setup.
A zero-install playground for students and tutorials across many languages.
Crunch numbers with Python (NumPy/Pandas) or R and render charts inline.
Create tables, insert and query with SQLite — your schema and data persist across visits.
Iterate on HTML/CSS layouts with a live preview beside the editor.
Paste JSON/XML/YAML/TOML and explore it as a tree, or jump to a converter.
JavaScript, TypeScript, Python, Ruby, R, HTML/CSS and SQL run live via WebAssembly. 25+ more languages (Java, Go, Rust, C++, C#, PHP, Kotlin, …) get full syntax highlighting and autocomplete but are edit-only — in-browser execution for compiled languages needs a server, which we avoid for privacy.
Yes. Everything runs entirely in your browser — no code is uploaded, there's no account, and nothing is executed on a server. It's ideal for sensitive snippets.
No. Just open the page and start coding. Language runtimes download once on first run, then are cached for instant reloads and offline use.
Yes. SQL runs on SQLite compiled to WebAssembly, and the database is stored in your browser (Origin Private File System). Create a table and insert rows, reload the page, and your data is still there.
The first run downloads that language's WebAssembly runtime (Python ~10 MB, Ruby ~29 MB, R ~30 MB) on a background thread — the editor stays responsive. After that it's cached, so subsequent runs start instantly.
Press Ctrl/⌘ + Enter, or click Run Code. Use the example buttons under the editor to load ready-to-run snippets for the selected language.