Pick a language
Choose JavaScript, TypeScript, HTML/CSS/JS, SQL or Lua. Each one opens with a working example.
Free Online Code Runner
Write code, press Run and see the output right away: console logs, tables, errors with line numbers. Build a web page with a live preview, practise SQL on a real SQLite database, or try Lua. Nothing to install.
Open Online Code Runner →How to run code online
Write your code
Type in the editor or open a file. Highlighting, indentation and closing brackets help as you go.
Run and share
Press Run or Ctrl+Enter to see the output. Save the file or copy a link to share your code.
Tips for the code runner
await works at the top level
In JavaScript and TypeScript you can write await outside a function, so trying out fetch-free async code is quick.
console.table for data
Pass an array of objects to console.table() to see it as a table you can download as CSV.
Each SQL run starts fresh
Put your CREATE TABLE and INSERT statements at the top: every run builds the database again, so results are repeatable.
TypeScript types aren't checked
Types are removed before the code runs, so a type mistake won't stop the program. Use it to try out syntax and logic.
Stop with Esc
An endless loop never freezes the page: press Stop or Esc and run again.
Lua numbers
Lua integers here are 32-bit, so very large whole numbers are best written as decimals.
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Online code runner FAQ
Which languages can I run?
JavaScript, TypeScript, HTML/CSS/JS with a live preview, SQL on SQLite, and Lua 5.3. For Python, use the free online Python compiler.
Is this online code runner free?
Yes. It is free, with no sign-up, no limits on runs and no watermark on anything you save.
Where does my code run?
In your browser, inside a sandbox that has no access to this site's cookies or storage. Your code isn't sent to a server to run.
Can I practise SQL here?
Yes. Write CREATE TABLE, INSERT and SELECT statements and see each result as a table. SQLite supports joins, window functions, recursive CTEs and JSON functions.
How do I see my HTML page?
Pick HTML/CSS/JS. Edit the HTML, CSS and JS tabs and the preview updates as you type; console messages from the page appear under it.
How do I share my code?
Press Share to copy a link. The code is stored in the link itself, so whoever opens it sees the same code in the editor.
Does my code stay here if I close the tab?
Yes. Your code for each language is saved in this browser and comes back when you return. Use Save to keep a file on your device.
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