Code Syntax Highlighter
Paste any code snippet and view it instantly with colorized syntax highlighting, then copy or download the result. Supports JavaScript, TypeScript, Python, PHP, HTML, CSS, JSON, YAML, SQL, Bash, Go, Rust, Java, C, C++, C#, Ruby, Swift, Kotlin, Markdown, XML and more.
Input
The highlighted preview currently renders using the default language shown here.
Output
Guides
What does this tool do?
It takes any code you paste in — a function, a config file, a query, a whole script — and displays it back with colorized syntax highlighting, so it's easier to read, review, screenshot or paste into docs, slides or a chat message. Pick the language you're working with from the dropdown, and copy or download the result when you're happy with it.
Supported languages
The tool covers the languages developers reach for most often: JavaScript, TypeScript, Python, PHP, HTML, CSS, JSON, YAML, SQL, Bash/Shell, Go, Rust, Java, C, C++, C#, Ruby, Swift, Kotlin, Markdown, XML, and Plain Text. That list keeps growing as more grammars get wired in.
How to use it
- Paste or type your code into the input box on the left.
- Choose the language from the Language dropdown.
- The highlighted result appears instantly on the right — no button to click.
- Use Copy to grab the code, or Download to save it as a text file.
Highlighting runs entirely in your browser as you type — there's no server round-trip and no waiting.
FAQ
Does the highlighting change color scheme per language I pick? The current preview renders using a single default highlighting scheme; picking a different language in the dropdown is captured for future output but doesn't yet re-color the live preview. The code itself is always passed through untouched (trailing whitespace trimmed, line endings normalized), so nothing about your snippet's content is altered — this only affects how it's colorized visually.
Will this reformat, minify, or lint my code? No. This is a display tool, not a formatter — it doesn't reindent, reorder, or rewrite your code. If you need formatting, look for a language-specific formatter tool (for example a JSON or SQL formatter).
Is there a size limit? No hard limit is enforced, but very large files (tens of thousands of lines) may render slowly in the browser since highlighting happens client-side.
Can I use this for embedding highlighted code snippets in a blog post or documentation? Yes — paste your snippet, copy the output, and drop it wherever you need clean, readable code. For HTML embedding with the exact colors baked in, use the download option and adapt the file to your site's styles.
Privacy
Your code never leaves your browser. Highlighting and processing happen entirely client-side — nothing is uploaded, logged, or stored on any server. This makes the tool safe to use even with proprietary or unpublished code.
Use it from code
From 3 credits per callREST API
curl -X POST https://api.iotools.cloud/v1/tool/code-syntax-highlighter \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"inputCode": "function add(a, b) {\n return a + b;\n}",
"language": "javascript"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `code-syntax-highlighter` tool (Code Syntax Highlighter) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.