Matomo HooksViewer Plugin

Description

Never install this plugin on a production instance. It is a development tool. Every page exposes internal arguments, appends to a log file, and adds DOM elements to Matomo's UI.

What it does

HooksViewer subscribes to every event Matomo dispatches and shows you, in real time, which hooks fire — where they fire, in what order, and with what arguments.

Two outputs run side by side:

1. Inline panel in the Matomo UI: each event is rendered as a <details><summary> block at the exact spot in the DOM where it was dispatched. Open the summary to see a pretty-printed, multi-line dump of the hook arguments. Widget XHRs (format=html) also surface their internal hooks like ViewDataTable.filterViewDataTable, Visualization.beforeRender, Metrics.isLowerValueBetter, etc.
2. Log file at tmp/logs/hooksviewer.log. Every hook from every request — including JSON API calls, tracker hits, and CLI commands — is appended with timestamp, request id, and arguments. Watch with tail -f tmp/logs/hooksviewer.log.

The plugin never injects markup into JSON, XML, CSV, image, or tracker responses, so Matomo's API stays valid and the dashboard, widgets, and third-party clients keep working.

How the hook list stays current

The list of subscribed events is discovered automatically by scanning core/ and plugins/ for Piwik::postEvent('…') call sites the first time the plugin runs (and whenever a source file is added/removed/edited). The result is cached in tmp/cache/hooksviewer-catalog.php.

You do not have to update the plugin when Matomo introduces new events — they show up the next time the cache is rebuilt.

Install

This plugin is published on the official Matomo Marketplace.

1. Open the Marketplace in your Matomo admin.
2. Search for HooksViewer.
3. Install, then activate.

Use

1. Activate the plugin while you are exploring or debugging.
2. Browse the page or trigger the workflow you care about.
3. Read the inline <details> blocks, or tail -f the log.
4. Deactivate the plugin when you are done.

Requirements

• Matomo 5.x
• PHP 7.4+

Author

Built by Openmost. Issues and pull requests welcome at https://github.com/openmost/HooksViewer.

License

GPL v3 or later.