Syntax Highlighter

Highlight code syntax online and copy ready-to-paste HTML for blogs and docs — free.

About

About the Syntax Highlighter

Turns a pasted code snippet into syntax-highlighted HTML, ready to copy into a blog post or documentation page.

Bloggers and technical writers use it to turn a plain code block into properly colored, readable code before publishing, while developers writing internal documentation use it to keep snippets consistent without installing an editor plugin. It's one of many free developer tools on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.

Choose what to view about this tool

Guide

Using the Syntax Highlighter

  1. 1

    Step 1

    Paste your code into the Code box.

  2. 2

    Step 2

    Choose a language, or leave it on Auto-detect, and pick a Light or Dark theme.

  3. 3

    Step 3

    Click "Highlight" — the highlighting library loads from this site the first time you use this.

  4. 4

    Step 4

    Click "Copy HTML" to copy the highlighted markup for pasting elsewhere.

  • Auto-detects the language, or lets you pick from 10 common languages
  • Light and dark color themes for the highlighted output
  • Produces ready-to-paste HTML with proper syntax-highlighting markup and classes
  • Tells you which language it detected when using Auto-detect
  • One click to copy the generated HTML
  • Runs entirely in your browser after its library loads — your code is never uploaded to a server
  • Free to use, with no sign-up and no limit on how many times you run it

Bloggers and technical writers

Bloggers and technical writers use the Syntax Highlighter for turning a plain code block into properly colored, readable code before publishing a post.

Developers writing docs

Developers writing internal documentation use the Syntax Highlighter for keeping code snippets visually consistent without an editor plugin.

Students

Students use the Syntax Highlighter for formatting code they're submitting in a report or presentation so it's easier to read.

Forum and Slack contributors

Forum and Slack contributors use the Syntax Highlighter for preparing nicely formatted code to paste into platforms that accept HTML.

Examples

Syntax Highlighter examples

3 worked examples

01

A JavaScript function

A short JavaScript function like function add(a, b) { return a + b; } highlights its function and return keywords in their own color, ready to paste as HTML.

02

A SQL query

"SELECT name, email FROM users WHERE active = 1 ORDER BY name;" with the Dark theme colors SELECT, FROM, WHERE and ORDER BY as keywords, separate from the table and column names.

03

Auto-detecting HTML

Leaving Language on Auto-detect for a snippet of markup like <div class="card">…</div> reports "Detected: HTML/XML" and colors tags and attributes separately.

Related tools

Regex Cheat Sheet

A searchable quick reference for common regular expression syntax.

Use it

SQL Formatter

Break a SQL query onto multiple lines at major keywords for easier reading.

Use it

JSON to TypeScript Interface Generator

Infer a TypeScript interface from a sample JSON object.

Use it

cURL Command Builder

Build a cURL command from a method, URL, headers and body.

Use it

JWT Encoder

Build and sign a JSON Web Token from a header, payload and secret.

Use it

cURL to Code Converter

Paste a curl command and get the same request as JavaScript, Python or Node.js code.

Use it

FAQ

Frequently asked questions

Quick answers to common questions about the Syntax Highlighter.

What does the Syntax Highlighter do?

It turns a pasted code snippet into syntax-highlighted HTML you can copy and paste anywhere that accepts HTML.

Is the Syntax Highlighter free to use?

Yes. It's free, with no sign-up, no watermark and no limit on how many times you use it.

Is my code uploaded anywhere?

The highlighting library itself (highlight.js) loads from this site the first time you use the tool, but the actual highlighting of your code runs entirely in your own browser afterward — your code is not sent to a server.

Which languages are supported?

You can pick from JavaScript, Python, PHP, HTML/XML, CSS, JSON, Bash, SQL, Java and C#, or leave it on Auto-detect and let the library guess.

How accurate is Auto-detect?

It's usually reliable for clearly distinct languages and larger snippets, but very short snippets or languages with similar syntax can occasionally be misdetected — picking the language explicitly is more reliable.

What do I do with the copied HTML?

Paste it into any page or editor that accepts raw HTML; you may also need to include a highlight.js theme stylesheet on that page for the colors to display correctly outside this tool.

Can I use this tool on my phone?

Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.

Does the Syntax Highlighter have any limitations?

It's built for typical code snippets rather than entire files; very large snippets may take a little longer to highlight.

Still have a question? Contact us

Report a problem

Syntax Highlighter

What went wrong?
    or paste a screenshot