Description
WebberZone Code Block Highlighting is the easiest way to add syntax highlighting to your WordPress site. It extends the native Gutenberg core/code block with Prism.js highlighting in the browser, or optional server-side highlighting with highlight.php — no shortcodes, no block replacement, no risk of breaking existing posts.
Simply activate the plugin and your code blocks will instantly display beautiful, readable syntax highlighting on the frontend. Choose from 40+ programming languages and 21 colour themes, all controlled from the block editor’s Inspector Controls sidebar.
Two highlighting modes
Pick the rendering mode that best fits your site from the settings page:
- Client-side (default) — Prism.js highlights your code in the browser. Best for interactive features such as copy-to-clipboard and expand/collapse.
- Server-side (highlight.php) — Code is pre-highlighted on the server with highlight.php, so no Prism.js or any other JavaScript is loaded for highlighting. Ideal for performance, Core Web Vitals, AMP-style setups, and strict content-security policies.
Both modes use the same 21 Prism themes and produce visually identical output, so you can switch between client-side and server-side rendering at any time without changing how your code blocks look.
Why use this plugin?
- Safe by design — Works as a filter on top of
core/codeand saves blocks with core’s own markup. Existing posts are never invalidated. Deactivate the plugin and your blocks are still valid standard WordPress code blocks. - Zero configuration — Activate and start writing. No setup wizard, no shortcodes.
- No highlighting JavaScript in server mode — Server-side mode pre-renders syntax colours on the server. No Prism.js or any other JavaScript is enqueued for highlighting.
- Smart asset loading — Theme CSS (and, in client mode, Prism JS) only load on pages that actually contain code blocks. Pages without code stay fast.
- Per-block controls — Set language, theme, line numbers, word wrap, title, highlighted lines, and max height individually for each block.
- Developer-friendly — Filters to add languages, override themes, and force asset loading.
Supported languages
40 languages including: Apache Config, Bash, C, C++, C#, CSS, Dart, Docker, F#, Go, GraphQL, Groovy, Haskell, HTML, Java, JavaScript, JSON, JSX, Kotlin, Lua, Markdown, Nginx, Objective-C, Perl, PHP, PowerShell, Python, R, Ruby, Rust, Sass, Scala, SQL, Swift, TOML, TSX, TypeScript, Vim, XML, YAML. Use the wzcbh_languages filter to add or remove entries from the language picker.
Included themes (21)
A11y Dark, Coldark Cold (Light), Coldark Dark, Dracula, Duotone Dark, Duotone Light, GitHub (Light), Gruvbox Dark, Gruvbox Light, Lucario, Material Dark, Material Light, Night Owl, Nord, One Dark, One Light, Shades of Purple, Solarized Dark, Synthwave ’84, VS Code Dark+, Xonokai (Monokai).
Per-block features
- Language selector — Choose the programming language from the sidebar; applies the correct Prism grammar automatically.
- Line numbers — Toggle line numbers per block, with a configurable start line.
- File title / label — Add an optional filename or label displayed in the code block toolbar.
- Highlight lines — Specify lines or ranges (e.g.
1,3-5) to visually highlight using Prism’s line-highlight plugin. - Max height with expand/collapse — Set a maximum height in pixels; an expand/collapse toolbar button appears automatically.
- Word wrap — Toggle soft word wrapping per block.
Global settings
- Highlighting mode — client-side (Prism.js) or server-side (highlight.php)
- Default colour scheme (theme)
- Default language
- Default line numbers toggle and start value
- Default word wrap
- Copy-to-clipboard button
- Show language label in toolbar
- Font size
Developer filters
wzcbh_languages— Filter the language list array (slug => label)wzcbh_color_scheme_css_url— Override the Prism theme CSS URLwzcbh_force_load_assets— Force Prism assets to load on every page
GDPR
WebberZone Code Block Highlighting does not collect personal data, set cookies, or communicate with any external services.
Contribute
The plugin is open source and available on GitHub. Pull requests for bug fixes and new features are welcome. Please use the WordPress.org support forum for support and GitHub Issues for confirmed bug reports.
Translations
Help translate WebberZone Code Block Highlighting into your language on WordPress.org. See the Translator Handbook for guidance.
Other plugins by WebberZone
- Contextual Related Posts — Display fast, intelligent related posts to keep visitors on your site longer
- Top 10 — Track daily and total visits and display popular and trending posts
- WebberZone Snippetz — Manage custom HTML, CSS and JS snippets across your site
- Knowledge Base — Create a knowledge base or FAQ section on your WordPress site
- Better Search — Contextual search results sorted by relevance
- Auto-Close — Automatically close comments, pingbacks, trackbacks and manage revisions
- Popular Authors — Display popular authors in a WordPress widget
- Followed Posts — Show related posts based on what your visitors have already read
- WebberZone Link Warnings — Add accessible warnings for external links and target=”_blank” links
Screenshots
Installation
WordPress admin (recommended)
- Go to Plugins > Add New in your WordPress admin.
- Search for WebberZone Code Block Highlighting.
- Click Install Now, then Activate.
Manual installation
- Download the plugin zip file.
- Extract it to your
wp-content/plugins/directory. You should end up with awebberzone-code-block-highlighting/folder. - Go to Plugins in your WordPress admin and activate WebberZone Code Block Highlighting.
After activation, open any post or page in the block editor, add or select a Code block, and the Code Highlighting panel will appear in the Inspector Controls sidebar.
FAQ
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Does this plugin replace the core Code block?
-
No. WebberZone Code Block Highlighting uses JavaScript and PHP filters to extend the native
core/codeblock. It never swaps the block for a custom one: the block is saved with the same markup as the core Code block, the highlighting options are stored as block attributes, and the language classes, file name, line numbers and max height are added when the page is rendered. -
Will my code blocks break if I deactivate the plugin?
-
No. Code blocks are saved with the core Code block’s own markup, so deactivating simply removes the highlighting and the blocks stay valid.
Blocks last saved with version 1.2.3 or earlier carry extra markup that the core block does not recognize, and show “This block contains unexpected or invalid content” if you deactivate the plugin before they are converted. To convert them, either open and update each post with the plugin active, or convert every post at once from the Convert Code Blocks link in the banner at the top of Settings > Code Block Highlighting, or with the WP-CLI command
wp wzcbh migrate-code-blocks. Back up your database first: posts are updated in place without creating revisions. -
Which programming languages are supported?
-
40 languages out of the box: Apache Config, Bash, C, C++, C#, CSS, Dart, Docker, F#, Go, GraphQL, Groovy, Haskell, HTML, Java, JavaScript, JSON, JSX, Kotlin, Lua, Markdown, Nginx, Objective-C, Perl, PHP, PowerShell, Python, R, Ruby, Rust, Sass, Scala, SQL, Swift, TOML, TSX, TypeScript, Vim, XML, and YAML.
Use the
wzcbh_languagesfilter to add or remove entries from the language picker. Note: adding a language to the filter only affects the UI dropdown — the corresponding Prism.js grammar must also be available on the frontend (either bundled infrontend.jsor loaded separately). -
How do I add a custom or additional Prism theme?
-
- Add the theme mapping in
build-prism.js. - Copy the generated CSS to
includes/assets/. - Register the slug in
includes/admin/class-settings.php. - Run
npm run build:prism.
You can also use the
wzcbh_color_scheme_css_urlfilter to point to any CSS file without touching the plugin source. - Add the theme mapping in
-
What is the difference between client-side and server-side highlighting?
-
In client-side mode (the default), Prism.js runs in the visitor’s browser and highlights your code on page load. This mode enables interactive toolbar features such as copy-to-clipboard and expand/collapse.
In server-side mode, the plugin uses highlight.php to pre-render the highlighted markup on the server. No JavaScript is loaded for highlighting, which is great for performance, Core Web Vitals, and sites with strict content-security policies. Both modes share the same 21 Prism themes and produce visually identical results, so you can switch freely from Settings > Code Block Highlighting.
-
Does server-side highlighting work without JavaScript?
-
Yes. When server-side mode is enabled, syntax colours are baked into the HTML on the server — no Prism.js or any other JavaScript is enqueued for highlighting.
-
Does Prism.js load on every page?
-
No. Theme CSS and (in client-side mode) Prism JS are only enqueued on pages that contain at least one code block. All other pages are unaffected. Use the
wzcbh_force_load_assetsfilter to override this behaviour if needed. -
How do I highlight specific lines in a code block?
-
Enter a comma-separated list of lines or ranges in the Highlight Lines field in the Inspector Controls sidebar (e.g.
1,3-5,8). This maps to thedata-lineattribute consumed by the Prism line-highlight plugin. -
Can I show a filename or label on the code block?
-
Yes. Use the Title field in the Inspector Controls sidebar. The label is displayed in the Prism toolbar above the code block.
-
Does the plugin support dark mode or multiple themes?
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The plugin ships with 21 Prism themes. The active theme is selected globally on the settings page (Settings > Code Block Highlighting). Per-block theme switching is not currently supported.
-
Is this plugin compatible with the WordPress block editor (Gutenberg)?
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Yes. The plugin is built specifically for the Gutenberg block editor (WordPress 6.6+) and uses the native block filter APIs. It does not support the Classic Editor.
-
Where do I report security bugs found in this plugin?
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Please report security bugs found in the source code of the WebberZone Code Block Highlighting plugin through the Patchstack Vulnerability Disclosure Program. The Patchstack team will assist you with verification, CVE assignment, and notify the developers of this plugin.
Reviews
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Contributors & Developers
“WebberZone Code Block Highlighting” is open source software. The following people have contributed to this plugin.
Contributors
Translate “WebberZone Code Block Highlighting” into your language.
Interested in development?
Browse the code, check out the SVN repository, or subscribe to the development log by RSS.
Changelog
1.3.0
Release date: 11 October 2026
Release post: https://webberzone.com/announcements/code-block-highlighting-v1-3/
Added
- Convert Code Blocks screen, linked from the settings page banner, and
wp wzcbh migrate-code-blocksWP-CLI command to convert code blocks saved by earlier versions in bulk. - Per-block color scheme option to override the global color scheme for a single code block, also stored by Save as default.
- Language detection for code blocks with no language set, in server-side mode. Turn on Detect Language in the settings; blocks that do not clearly match a language stay plain.
Changed
- Save as default now also stores the block’s download button setting.
Fixed
- Code blocks with a language, file name, highlighted lines, max height or custom start line showed “This block contains unexpected or invalid content” after the plugin was deactivated. Blocks saved by earlier versions convert when their post is updated.
- In server-side mode, a custom start line was ignored when the block also had a max height or a spacing style.
- Code blocks inside synced patterns, widgets or templates were not highlighted when the post content itself had no code block.
- Opening a post in the editor applied the saved block defaults to its existing code blocks and marked the post as changed. Defaults now apply only to newly inserted blocks.
Earlier versions
For the changelog of earlier versions, please refer to the releases page on GitHub.