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HookTrace – Trace Hooks with Precision

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HookTrace – Trace Hooks with Precision

by SmilingSyntax

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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_DEBUG must be set to true in wp-config.php
  • User must have manage_options capability (administrator)
  • PHP 8.0 or higher

Safety Features:

  • Automatically disables when WP_DEBUG is false
  • Never runs for non-admin users
  • Never modifies WordPress behavior
  • Observational only – no code execution changes
  1. Upload the hooktrace folder to /wp-content/plugins/ directory
  2. Activate the plugin through the ‘Plugins’ menu in WordPress
  3. Ensure WP_DEBUG is set to true in your wp-config.php file
  4. (Optional) For early hook capture, copy hooktrace-bootstrap.php from the plugin directory to /wp-content/mu-plugins/
  1. Hook list view showing all hooks that fired, with search and filter options

    Hook list view showing all hooks that fired, with search and filter options

  2. Selected hook detail view showing all callbacks with priority, execution order, duration, and file paths

    Selected hook detail view showing all callbacks with priority, execution order, duration, and file paths

  3. Color-coded badges indicating source (core/theme/plugin) and type (action/filter)

    Color-coded badges indicating source (core/theme/plugin) and type (action/filter)

Does this plugin work in production?

No. This plugin is designed exclusively for development and staging environments. It requires WP_DEBUG to be enabled and will automatically disable itself if WP_DEBUG is false.

Will this slow down my site?

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.

Do I need to install the MU-plugin bootstrap?

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.

Can I use this to debug plugin conflicts?

Yes! The timeline view shows which hooks fire and which plugins are registering callbacks, making it easier to identify conflicts and execution order issues.

Does this modify WordPress behavior?

No. This plugin is purely observational. It never modifies hook execution, suppresses errors, or changes WordPress behavior in any way.

What data is stored?

No data is stored. All trace information is kept in memory for the current request only and is discarded after the page loads.

How do I inspect a specific hook?

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.

Brilliant!

By Bowo (qriouslad) on January 12, 2026

I think this is a brilliant piece of dev tool!

Although Query Monitor has something similar, this plugin has a singular focus and thus, have a wider possibility to be useful in this particular area of seeng and analyzing what's happening on each and every hook fired. Looking forward to explore using it more in my dev workflow.

Thank you for developing it.

1.1.0

  • Added local editor integration – Open files directly in your favorite IDE (VS Code, PhpStorm, Sublime Text, Atom, Cursor, Antigravity, or custom protocol)
  • Added settings page (Tools HookTrace) for configuring local editor and path mapping
  • Added function filter for single hook tracing – Filter callbacks by function name
  • Added execution statistics – Display min, max, avg, and total execution time for filtered functions
  • Improved callback execution tracking – Each callback execution is now tracked separately with accurate timing
  • Enhanced UI/UX – Single scroll area, sticky filter and stats, more compact callback items
  • Improved labels – Full descriptive words instead of abbreviations (Priority, Execution Order, etc.)
  • Added translation support – All strings are now translatable with POT file included
  • Added dual editor links – Display both local editor and WordPress editor links when available
  • Improved modal positioning – Aligned to top to prevent flickering with dynamic content

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
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