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JSON Syntax Highlighting

Paste JSON to validate, pretty-print, and turn it into syntax-highlighted HTML. Choose a light or dark theme, toggle line numbers, and copy the highlighted snippet for docs, blogs, or internal tools.

FreeNo signupBrowser basedPrivate

Last updated: May 28, 2026

Client-Side Processing
Input Data Stays on Device
Instant Local Execution
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What is JSON Syntax Highlighting?

JSON syntax highlighting adds color to keys, strings, numbers, booleans, null values, and punctuation so JSON is easier to scan. It is useful for documentation, tutorials, changelogs, API examples, and debugging notes where plain JSON would be hard to read.

This tool first parses JSON strictly, then formats it with consistent indentation and emits escaped HTML. Because values are escaped before highlighting, pasted JSON is treated as source text rather than executable markup.

How to Use JSON Syntax Highlighting

1

Paste valid JSON into the input panel.

2

Choose dark or light highlighting.

3

Pick the indentation size and whether to show line numbers.

4

Preview the highlighted result.

5

Copy the generated HTML, copy formatted JSON, or download an HTML file.

Common Use Cases

  • Create highlighted JSON examples for API documentation.
  • Format configuration snippets for internal runbooks or wikis.
  • Prepare readable JSON samples for blog posts and tutorials.
  • Review JSON structure with line numbers during debugging.
  • Generate lightweight highlighted HTML without a client-side library.

Example Input and Output

A JSON API status object is formatted and wrapped in highlighted HTML.

JSON input
{ "healthy": true, "latencyMs": 84.7, "burst": null }
Highlighted HTML
<pre><code><span style="color:#9cdcfe">&quot;healthy&quot;</span>: <span style="color:#569cd6">true</span></code></pre>

Privacy

JSON input is parsed and highlighted in the browser. It is not uploaded.

Embedding output

The copied HTML uses inline styles so it can be pasted into many CMS editors and documentation systems without requiring an external stylesheet.

Frequently Asked Questions

Does this validate JSON?

Yes. The tool uses strict JSON parsing before highlighting and shows parse errors when the input is invalid.

Can I copy only formatted JSON?

Yes. Switch to the Formatted tab and copy the pretty-printed JSON output.

Is the highlighted HTML safe to embed?

Cell content is HTML-escaped before spans are added, so pasted JSON text is not inserted as raw HTML.

Can I hide line numbers?

Yes. Turn off the line number option before copying or downloading the highlighted HTML.

Is data sent to a server?

No. Formatting and highlighting run locally in your browser.

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