▶ Coding Playground
5 live coding sandboxes — write HTML/CSS/JS, preview Markdown, format SQL, run JavaScript and test APIs. Everything runs in your browser.
Free Online Coding Playground — Write, Run & Preview in Your Browser
This online coding playground lets you write, run and preview code with zero setup. The HTML/CSS/JS live editor, Markdown editor, SQL formatter, JavaScript playground and API request tester all run 100% client-side — no account, no install, and your code never leaves your browser. Perfect for quick experiments, snippets and interview practice.
HTML/CSS/JS Live Editor
Write HTML, CSS and JavaScript in three panes and see the result update instantly in a sandboxed live preview iframe. Great for prototyping components, testing layouts and learning front-end development without a build step.
Markdown Editor + Preview
Type Markdown on the left and watch the rendered HTML on the right. The built-in parser supports headings, bold, italic, links, images, lists, blockquotes, inline code and code blocks — all without any external library.
SQL Formatter
Paste unformatted SQL and click Format to uppercase keywords and place major clauses like SELECT, FROM, WHERE, JOIN and ORDER BY on their own lines. String literals are preserved.
JavaScript Playground
Run JavaScript and see console.log output immediately. A sandboxed console captures log, warn and error output, so you can test snippets and logic without opening dev tools or a terminal.
API Request Tester
Test REST API endpoints directly from your browser. Choose a method, set headers and a body, then send to view the status code, response headers and body (auto-formatted for JSON). CORS-restricted targets are flagged with a clear message.
Need to format data first? Visit the developer tools for JSON, JWT and Base64, or the calculators for quick finance maths.
Frequently Asked Questions
Does the playground require a sign-up or installation?
No. All five playgrounds run entirely in your browser with no sign-up, no install and no server-side processing.
Is my code sent to a server?
No. Your code stays in your browser. The live editor and JS playground execute locally, and the API tester makes requests only to the URL you enter yourself.
Can I save my code from the playground?
The playground keeps code in your current tab. To keep it, copy the contents into your own files. No data is stored or transmitted anywhere.
Why did my API request fail with a CORS error?
Browsers block cross-origin requests unless the target server allows them. If a request fails, the server probably does not send CORS headers. The tester shows a clear CORS message so you can confirm the cause.
Does the live HTML editor support external libraries?
Yes — you can add <script> tags for CDNs inside the HTML pane, and the preview will load them like a normal page.
Which Markdown features are supported?
Headings, bold, italic, links, images, ordered and unordered lists, blockquotes, inline code and fenced code blocks. It is a lightweight, dependency-free parser.