This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

iG:Syntax Hiliter


iG:Syntax Hiliter allows you to post source code to your site with syntax highlighting and formatting (as seen in code editors, IDEs). You can paste the code as is from your code editor or IDE and this plugin will take care of all the code colouring and preserve your formatting. It uses the GeSHi library to colourize your code and supports over a 100 programming languages. Most common languages are included with the plugin and it includes drop in support for more languages used by GeSHi.

NOTE : For fast results and less load on your server, you should have a cache plugin installed. That way the plugin won’t have to parse the code blocks on a post every time its loaded in browser.

Minimum Requirements

  • WordPress 4.1 or above
  • PHP 7.4.0 or above

Pull requests are welcome on Github.

Documentation on plugin usage and configuration


  • Settings page of the plugin where default options can be set for plugin
  • Example display of syntax highlighted PHP code
  • Example display of plain text view of some PHP code


UPGRADING from v4.0 or later

Just click update now link below the plugin listing on the plugins page in your wp-admin. That’s quite easy!!

UPGRADING from v3.x

Just deactivate plugin in WordPress admin, delete the syntax_hilite.php file & ig_syntax_hilite directory from plugins folder and follow the installation process below. That’s quite easy!!

UPGRADING from v2.1 or lower

Just deactivate plugin in WordPress admin, delete the syntax_hilite.php and geshi.php files & geshi directory from plugins folder and follow the installation process below. That’s quite easy!!

Installing The Plugin

  1. Login to your WordPress wp-admin area.
  2. Click Add New in the Plugins menu on left.
  3. Enter iG:Syntax Hiliter in the search bar on the right on the page that opens and press Enter key.
  4. WordPress would show the iG:Syntax Hiliter plugin with install button, click that to install the plugin.
  5. Click on Activate Plugin link on the page that opens after the plugin has been installed successfully.

See Also: “Installing Plugins” article on the WP Codex


My code looks all odd, characters appear as HTML entities. Why is your plugin screwing up my code?

If you are using the WYSIWYG (rich text) editor to compose your post then that is what’s messing things up for you. iG:Syntax Hiliter does not support composing posts and posting code using WYSIWYG at present. If you are not using WYSIWYG editor and still have same issue, please report it.

I see some code that I can improve. Do you accept pull requests?

By all means, feel free to submit a pull request.

I want XYZ feature. Can you implement it?

Please feel free to suggest a new feature. Its inclusion might be speedier if you can provide the code to make it work.


There are no reviews for this plugin.

Contributors & Developers

“iG:Syntax Hiliter” is open source software. The following people have contributed to this plugin.


Translate “iG:Syntax Hiliter” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.



  • Minimum required PHP version bumped to 7.4.0. The plugin simply won’t load its code on lower versions.
  • Refactored plugin code for PHP 7.4.x for better performing code.
  • This is the last release using the GeSHi library. GeSHi library has not been updated in several years and it looks unlikely that it will continue. Next release of the plugin will use a different syntax highlighting library. All existing shortcodes will continue to work and so the update and transition would be seamless for the most part, except a feature or two that will phase out and a few changes in plugin configuration options.


  • Minimum required PHP version bumped to 5.3.0. The plugin simply won’t load its code on lower versions.
  • Major re-write of plugin for cleaner, modular & better performing code.
  • Assets are enqueued only if needed.
  • NEW: You can now disable plugin stylesheet which styles code boxes. People who have their own styling don’t need it anyway.
  • NEW: 2 new options allow more control on GeSHi behaviour.
  • BUGFIX: Language name cache was not re-building automatically.


  • BUGFIX: some language file names got snipped when building language name cache


  • BUGFIX: Shorthand tags for all languages supported now – props to Karol Kuczmarski for spotting it
  • NEW: Added C++ language file


  • BUGFIX: Github Gist URL XSS security hole
  • BUGFIX: __dir__ doesn’t work below PHP 5.3 – props to Karol Kuczmarski for spotting it
  • NEW: Added “lang” as shorthand for “language” attribute
  • NEW: Additional GeSHi language files can be put in “geshi” directory in theme, which will prevent their deletion on plugin upgrade
  • IMPROVED: If a code block is repeated with same attributes then its parsed only once and output is reused


  • NEW: Ability to embed Github Gist in post and comments (configurable)
  • NEW: Ability to highlight one or multiple lines in a code block to show them as different
  • NEW: New code box layout
  • NEW: Ability to escape plugin tags to prevent their processing
  • NEW: New GeSHi core (v
  • IMPROVED: Removed quirks from plain text view & its now much more smoother
  • IMPROVED: Handling of how code is prevented from beautification. The rest of the post/comment text is not affected as wptexturize is not removed anymore.
  • IMPROVED: Simpler and faster options page in wp-admin


  • BUGFIX: BB Tags except the ones of iG:Syntax Hiliter are allowed. The language file’s existence is checked before parsing the code. If the language file does not exist then the code is not parsed.
  • BUGFIX: ‘C’ code hiliting is now fixed.
  • BUGFIX: ‘Plain Text’ has been improved to strip the extra blank lines and spaces in Opera and FireFox.
  • The latest stable GeSHi core(v1.0.7.6).
  • NEW: Code Hiliting for Comments has been implemented. This feature can be Enabled/Disabled from the admin interface for iG:Syntax Hiliter. The tags are same for hiliting the code.
  • NEW: A cross-browser Colour Picker(tested in IE6, FireFox1.5 and Opera8.5) is now available to easily set the line colours displayed in the code box.
  • NEW: A new type of view implemented for seeing “Plain Text” code. Besides opening the plain text code in a new window, you can have it displayed in the code box itself with an option to display the hilited HTML code back again. The “Plain Text” view type can be set in the admin interface.
  • The language file for Ruby that I created a while back is now bundled with the plugin and its also a part of the default GeSHi package.


  • BUGFIX: Critical bug, which broke the plugin when the square brackets([ & ]) were used in the posts in places other than tags, has been fixed.
  • BUGFIX: Another bug, which allowed any attribute in the tags besides the ‘num’ and also allowed any attribute value for it, affecting the processing. Now only the ‘num’ attribute is accepted and if you specify the ‘num’ attribute then its value must be a positive number otherwise your code won’t be hilited. The ‘num’ attribute is optional and you can leave it out without any problems.
  • BUGFIX: Fixed the unclosed tags in the Plugin GUI code.
  • GeSHi BUGFIX: Fixed a bug in GeSHi where the first line colour was not used when using FANCY LINE NUMBERS thus resulting in just one colour being used for the alternate lines.
  • There’s a problem in WordPress due to which the starting delimiters of ASP, PHP were not displayed correctly, as whitespace was inserted between the ‘<‘ and the rest of the delimiter. This has been patched so that its displayed correctly, but its not saved in the database, so the database still contains the delimiters as formatted by WordPress.


  • Complete re-write of the plugin resulting in reduction of code from 750+ lines to about 400 Lines.
  • New GeSHi Core(v1.0.7) which has some bug-fixes, please see GeSHi Website for its changelog.
  • New languages added are C#, Delphi, Smarty & VB.NET.
  • ASP language file structure updated & more keywords added.
  • Drag-n-Drop usage of new languages. The plugin now supports all languages that GeSHi(v1.0.7) supports. You just need to drop the language file in the “geshi” directory & use the filename as the tag for the language(like if file is “pascal.php”, then the filename is “pascal” & the tags will be


  • Language name which is displayed in the Code-Box can now be turned ON or OFF easily.
  • No more need to set the physical-path to the “geshi” directory if you are doing a default installation.
  • Plain-Text View of the code hilited in the code-box is now possible. This feature can be enabled/disabled easily in the Configuration Interface in WordPress Administration.
  • NO NEED TO EDIT THE PLUGIN FILE ANYMORE. You can now configure the plugin settings from a GUI located under the OPTIONS menu in your WordPress Administration(WordPress 1.5 & above only).


  • BUGFIX: Fixed a bug by removing a
    tag from the function pFix() which lead to closing of an unnecessary

    tag making the code not xHTML valid(as per my desires).

v2.0 Final

  • Implemented the new version of GeSHi core, v1.0.2 which has some bug fixes & which uses OL(Ordered Lists) for Line Numbering and supports starting of a Line Number from any given number.
  • The ASP(Active Server Pages) language file has been updated to the new Language File structure of GeSHi as well as more keywords added & hiliting is more effective now.
  • iG:Syntax Hiliter now also supports ActionScript, C, C++, JavaScript, Perl, Python, Visual Basic & XML.
  • The whole plugin has been re-written & all the hiliting code is now in a class. You can just use the class anywhere else too for hiliting the code. But to also use the Code Tags to wrap your code & then hilite them, you will need to use all other functions. You can remove the WordPress Filter calls at the end of the plugin & use the rest of the code as you want somewhere else.
  • BUGFIX: The issue of multi-line comments not being hilited properly in v2.0 Preview has been sorted out.

v2.0 Preview

  • Implemented the new version of GeSHi core, v1.0.1 which has some bug fixes including the extra quote(“) bug that broke the xHTML validation of the code.
  • I’ve created a new language file for ASP(Active Server Pages) which has been added to this release & will also be a part of the next GeSHi release.
  • Line numbering is now done through Ordered Lists(
      ) & the code is xHTML compliant.
  • Auto-Formatting disabled for posts that contain the iG:Syntax Hiliter code tags so that your code is good for copy-paste operations.


  • Implemented the line numbering of code.
  • The code box is now of fixed dimensions without word-wrap & with scrollbars(if required).


  • Hilites code between the special tags, all of them differently.
  • Uses GeSHi for syntax hiliting.
  • Supports HTML, CSS, PHP, JAVA & SQL codes.