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Documentation WebP converter plugin for Joomla

 

 

Compatibility:   J5 j6
Extension type:   plugin icon
Version:   1.2.3 (july 2026)
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WebP Converter Plugin

Automatic Image Conversion to WebP for Joomla 5 and 6

WebP Converter is a Joomla system plugin that automatically converts uploaded PNG and JPG images to WebP format. The conversion happens silently after upload via the Joomla Media Manager, helping reduce image size, improve page speed, and enhance SEO without changing your workflow.

Requirements

  • Joomla 5.0 or higher (also compatible with Joomla 6)
  • PHP 7.4 or higher
  • PHP GD library with WebP support enabled, or Imagick as a fallback
  • Administrator access to your Joomla website
  • Writable /images directory and subfolders

Installation

  1. Log in to your Joomla administrator panel
  2. Navigate to System → Install → Extensions
  3. Select the Upload Package File tab
  4. Click Browse and select the downloaded plugin ZIP file
  5. Click Upload & Install
  6. Navigate to System → Manage → Plugins
  7. Find WebP Converter (System plugin)
  8. Enable the plugin
  9. Open the plugin settings to configure the options (see below)

Manual Installation

  1. Unzip the downloaded package on your computer
  2. Using FTP, upload the webpconverter folder to:
    /plugins/system/
  3. Log in to your Joomla administrator panel
  4. Navigate to System → Discover
  5. Find WebP Converter and click Install
  6. Navigate to System → Manage → Plugins
  7. Enable and configure the plugin

Plugin settings

Basic Settings

Enable Conversion
Enable or disable WebP conversion globally. When disabled, no images will be processed.

Image Conversion Settings

Supported Formats
The plugin automatically converts the following formats:

  • PNG
  • JPG / JPEG
  • Other formats are ignored.

WebP Quality

Set the quality level for generated WebP images.
Lower values produce smaller files, higher values preserve more detail.

Recommended values:

  • 75–80 for maximum compression
  • 85–90 for balanced quality
  • 95 for near-lossless results

Original Image Handling

Keep Original Image
Choose what happens to the original PNG or JPG after conversion.

Enabled:
The original file is kept alongside the WebP image.

Disabled:
The original file is removed after successful conversion. Joomla's Media Manager now correctly shows the converted WebP file immediately, no manual refresh needed.

This setting only affects newly uploaded images.

Max File Size:

Skip conversion for files larger than this size. Set to 0 for no limit. Default: 10 MB.

Use this to avoid spending server resources converting very large source images, or to exclude specific bulk-upload workflows from automatic conversion.

Conversion Library

Choose which image library performs the WebP conversion:

  • Auto Detect (default) — prefers GD, and automatically falls back to Imagick on hosts where GD lacks WebP support.
  • GD Library — force GD.
  • Imagick — force Imagick.

If neither library is available or WebP-capable, conversion fails safely: the original file is left untouched and the failure is logged (see Troubleshooting).

Update References

This setting is present in the plugin configuration but reserved for future use. Rewriting file references across articles and custom fields is a larger, separate feature, it does not currently do anything. We'll update this documentation when it ships.

Media Manager Integration

Upload Scope
The plugin listens for uploads via the Joomla Media Manager.

  • Images uploaded to /images are converted
  • Images uploaded to any subfolder of /images are also converted
  • The WebP file is created in the same folder as the original image.

Conversion Behavior

New Uploads Only
The plugin processes only newly uploaded images.
Existing images are never modified or converted automatically.

This ensures safe installation on live websites without unexpected changes.

EXIF Orientation

Photos uploaded straight from phones and cameras keep their correct orientation after conversion — EXIF orientation data is read and preserved, so images no longer appear rotated incorrectly.

How it Works

  1. Upload a PNG or JPG image via the Joomla Media Manager
  2. The plugin detects the upload via Joomla's own media-save event
  3. The plugin detects the upload
  4. A WebP version is generated automatically
  5. The WebP file is saved in the same folder
  6. No manual action is required.

Compatibility

  • Joomla 5
  • Joomla 6
  • Works with Media Manager subfolders
  • Compatible with caching, CDN, and performance extensions
  • Does not store data or logs in the database (logging only occurs if conversion fails, see Troubleshooting)

FAQ

Frequently Asked Questions (FAQ)

1. Do I need to enable WebP uploads in Joomla settings?
No. The plugin generates WebP files on the server. Joomla upload settings are only relevant if you manually upload .webp files.

2. Will this convert existing images?
No. Only new uploads are processed.

3. Does it work on shared hosting?
Yes, as long as PHP GD or Imagick supports WebP.

4. What happens if WebP is not supported by the server?
The image will not be converted. The original file remains untouched, and the failure is logged in the Joomla admin logs.

5. Will this affect my website layout?
No. The visual appearance remains the same. Only file size changes.

Troubleshooting

No WebP file is created

  • Verify that a WebP-capable library is available (PHP GD with WebP support, or Imagick)
  • Check administrator/logs/plg_system_webpconverter.php for a logged failure reason
    Check folder write permissions
  • Ensure the image is uploaded via the Media Manager

Works in root but not in subfolders

  • Ensure the plugin is enabled
  • Confirm the upload is done through the Media Manager, not FTP

WebPconverter — Changelog

1.2.3 — July 2026

Changes since 1.0.

Changed

  • Upload detection now hooks Joomla's onContentAfterSave event directly (context com_media.file) instead of scanning /images for recently modified files. Removes false triggers from unrelated Media Manager actions (delete, rename, create folder) and prevents simultaneous uploads by different users from cross-converting each other's files.
  • Conversion runs synchronously as part of the upload request, so the Media Manager grid can refresh reliably right after upload instead of racing a background job.

Added

  • Imagick support: the "Conversion library" setting (Auto Detect / GD / Imagick) now actually applies. Auto Detect prefers GD and falls back to Imagick automatically on hosts where GD lacks WebP support.
  • EXIF orientation is preserved during conversion — photos from phones and cameras no longer end up rotated incorrectly.
  • Conversion failures (no WebP-capable library available) are now logged to administrator/logs/plg_system_webpconverter.php and shown as an admin warning, instead of failing silently.
  • The Media Manager grid auto-refreshes after upload to show the converted file immediately.

Fixed

  • Corrected Joomla's own upload response so it no longer references the original file after it's been deleted, this previously caused a "File or Folder not found" notice in the Media Manager right after upload when "Keep original" was off.

Unchanged (by design)

  • "Update references" stays reserved for future use, rewriting file references across content and custom fields is a larger, separate feature.
  • Still JPG/PNG only; animated GIFs are intentionally not converted (would be flattened to a static frame).
  • No bulk-convert for existing images, conversion still triggers on new uploads only.

Compatibility

Joomla 5.x and 6.x. No settings changes required for existing installs, upgrades in place via the Joomla installer.

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