Description
HookTrace is a developer observability tool that records and visualizes the runtime execution order of WordPress hooks, filters, and plugin initialization for a single page request.
For Developers Only
This plugin is designed exclusively for development and staging environments. It helps developers understand:
- Which hooks fired, in what order
- Which callbacks executed on each hook
- Callback priority and execution time
- Source plugin, theme, or core location
- Exact file and line number
- Plugin and theme load timeline
Key Features:
- Hook List Tracking – Records all hooks that fire during a page request with type and source information
- Detailed Callback Inspection – When a hook is selected, displays comprehensive callback information including priority, execution order, duration, file path, and source
- Modern Modal UI – Beautiful, searchable interface with filtering capabilities
- Zero Performance Impact – In-memory storage only, no database writes
- Early Boot Support – MU-plugin bootstrap captures hooks from the very beginning
Requirements:
WP_DEBUGmust be set totrueinwp-config.php- User must have
manage_optionscapability (administrator) - PHP 8.0 or higher
Safety Features:
- Automatically disables when
WP_DEBUGis false - Never runs for non-admin users
- Never modifies WordPress behavior
- Observational only – no code execution changes
Screenshots
Hook list view showing all hooks that fired, with search and filter options 
Selected hook detail view showing all callbacks with priority, execution order, duration, and file paths 
Color-coded badges indicating source (core/theme/plugin) and type (action/filter) 
Installation
- Upload the
hooktracefolder to/wp-content/plugins/directory - Activate the plugin through the ‘Plugins’ menu in WordPress
- Ensure
WP_DEBUGis set totruein yourwp-config.phpfile - (Optional) For early hook capture, copy
hooktrace-bootstrap.phpfrom the plugin directory to/wp-content/mu-plugins/
FAQ
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Does this plugin work in production?
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No. This plugin is designed exclusively for development and staging environments. It requires
WP_DEBUGto be enabled and will automatically disable itself ifWP_DEBUGis false. -
Will this slow down my site?
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The plugin is designed with minimal overhead (5-10ms average). However, it should only be used in development/staging environments where performance is not critical.
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Do I need to install the MU-plugin bootstrap?
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The MU-plugin bootstrap is optional but recommended. It allows the plugin to capture hooks from the very beginning of WordPress initialization, including must-use plugins and early core hooks.
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Can I use this to debug plugin conflicts?
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Yes! The timeline view shows which hooks fire and which plugins are registering callbacks, making it easier to identify conflicts and execution order issues.
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Does this modify WordPress behavior?
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No. This plugin is purely observational. It never modifies hook execution, suppresses errors, or changes WordPress behavior in any way.
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What data is stored?
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No data is stored. All trace information is kept in memory for the current request only and is discarded after the page loads.
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How do I inspect a specific hook?
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Click on any hook in the list to see detailed information about all callbacks registered for that hook, including priority, execution order, duration, and source file location.
Reviews
Contributors & Developers
“HookTrace – Trace Hooks with Precision” is open source software. The following people have contributed to this plugin.
Contributors
Translate “HookTrace – Trace Hooks with Precision” into your language.
Interested in development?
Browse the code, check out the SVN repository, or subscribe to the development log by RSS.
Changelog
1.0.0
- Initial release
- Hook list tracking (all hooks that fire)
- Detailed callback inspection for selected hooks
- Modern modal UI with search and filtering
- Admin bar integration
- MU-plugin bootstrap support
- Color-coded badges for source and type identification
- Responsive design with smooth animations
