Paste code. Preview it instantly.
A free browser workspace for HTML, CSS, JavaScript, JSON, XML, Python, PHP, SQL and more. Web code renders live in an isolated preview; everything else is displayed clean for reading, copying and exporting.
Code workbench
1 line · nothing you paste leaves this tab
Three steps, then you're testing.
No project to set up, no dependencies to install — just a tab and a language picker.
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Paste your code
Drop in code from your project, a tutorial, documentation or the clipboard. It stays in the editor pane, in your browser only.
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Choose a language
Pick the language that matches what you pasted. HTML, CSS and JavaScript unlock the live preview; everything else displays as formatted source.
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Run, copy or export
Press run preview to render web code, or use copy and download to take the source with you — as-is, no account required.
What the preview can and can't do.
Rendering someone else's code in your browser deserves a plain explanation, not a vague "your data is safe" line.
Sandboxed preview
HTML, CSS and JavaScript run inside an iframe with scripting allowed but same-origin access denied, so pasted code can't reach this page or your other tabs.
Server-side code isn't executed
Python, PHP, Java, C and the rest are shown as clean formatted source for reading and copying — this page never runs them anywhere.
Nothing uploaded
The editor and preview run entirely client-side. Refresh the tab and the code is gone — there's no draft saved anywhere to clean up.
Multiple languages, two behaviors.
Browser-native web code renders live. Everything else is shown as formatted, copyable source rather than executed.
Live preview
HTML · CSS · JavaScript
Rendered instantly in the sandboxed iframe.
Data
JSON · XML · YAML
Displayed as formatted source.
Backend
Python · PHP · Java
Source view only, not executed.
Systems
C · C++ · C# · Bash
Source view only, not executed.
Database
SQL
Source view — for a working scratch database, use the SQL editor.
Typed web
TypeScript
Displayed as formatted source.
Documentation
Markdown
Displayed as formatted source.
General
Plain text
Displayed exactly as pasted.
What this tool is for.
A convenient scratchpad, not a replacement for a real development environment.
An online code editor is useful when you want to test a small HTML, CSS or JavaScript example without opening a full project, or when you need to read and copy a snippet in another language without an IDE nearby.
KRHTech also supports source inspection for programming, database, configuration and markup languages. These are displayed as formatted code rather than executed, which is a deliberate limit, not a missing feature.
Who ends up here.
The same handful of situations come up again and again.
Checking a snippet from a tutorial
Paste an example, watch it render, and confirm it does what the article claims before copying it into a real project.
Isolating a CSS or layout bug
Stripping a problem down to a minimal HTML and CSS pair here is often faster than reproducing it inside a full build.
Reading code on a locked-down machine
On a shared or managed computer without an editor installed, this is often the fastest way to read, format and copy a file.
Questions people ask.
If something here isn't covered, the contact details are on the homepage.
Can I paste code directly into the editor?
Yes. Paste your code into the editor, select its language, and use run preview for HTML, CSS or JavaScript.
Can I run Python, PHP or Java code here?
No. Those languages are available for source editing, formatting and copying, but this browser tool does not execute server-side languages.
Is the code I paste sent to a server?
No. Everything happens locally in your browser tab, including the preview. Nothing you paste is uploaded, logged or stored.
Is it safe to preview JavaScript from an unknown source?
The preview runs inside a sandboxed iframe with same-origin access denied, which limits what pasted code can reach. Even so, never paste passwords, API keys or other secrets into any online tool.
Is the online code editor free?
Yes. The tool is free to use, needs no account, and is funded by advertising rather than subscriptions.
Other tools on the bench.
Six more single-purpose utilities, all free and running the moment you open them.