100% Free & Open Source - Forever

Supercharge Your WordPress SEO & Speed.

The ultimate lightweight WebP optimizer. Convert images locally, protect your privacy, and boost Core Web Vitals without spending a dime.

📥 Download Plugin View Source

Why Choose Jacker OneWebP?

Stop paying for image optimization. Stop uploading your private images to strangers' servers.

❌ Traditional API Plugins

  • 💸 Monthly limits & expensive subscriptions
  • 🔓 Privacy risks (images sent externally)
  • 🐌 Slow processing due to network latency

✅ Jacker OneWebP Local Engine

  • 🆓 100% Free, Unlimited conversions
  • 🔒 100% Privacy (Images stay on server)
  • ⚡ Instant local processing via PHP GD

Powerful Features, Zero Bloat

Engineered for performance, privacy, and ease of use.

100% Local & Private

No third-party APIs. Your images are processed directly on your server using native PHP GD. Maximum privacy.

Smart Memory Engine

Dynamically calculates memory requirements and adjusts batch sizes. Prevents 502 errors on shared hosting.

Smart Queue Lazy Load

Boosts LCP scores. Critical images load instantly with fetchpriority="high", others lazy-load via smart queue.

First N Direct Load

The most effective fix for LCP warnings. Controls how many top-of-page images skip lazy loading and load eagerly with high priority.

Auto Downscaling

Automatically resizes massive images (e.g., >3000px) during conversion. Saves bandwidth effortlessly.

One-Click Dashboard

Beautiful, native WordPress UI. Real-time stats, progress bars, and bulk optimization with a single click.

Server Health Monitor

Proactive warnings for low disk space (under 500MB) and RAM (under 64MB). Prevents disasters before they happen.

Built to Crush Core Web Vitals

Google prioritizes fast, lightweight websites. Jacker OneWebP is specifically engineered to improve your Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS).

  • Converts heavy JPG/PNG to next-gen WebP (up to 80% smaller).
  • Smart Lazy Loading ensures above-the-fold images load instantly.
  • First N Direct Load fixes LCP warnings from page builders.
  • Zero external scripts means no render-blocking resources.
  • Progressive Loading: Blurry preview, sharp image in under 500ms.
Largest Contentful Paint (LCP)
1.2s (Excellent)
Total Page Weight Reduction
-65% (Lightweight)

Experience the Interface

Native WordPress design. Click the tabs to explore the actual plugin pages.

📊 Dashboard
⚙️ Settings
🖼️ Image Manager
156 Total Images
134 Converted
8 Already WebP
10 Pending
4 Failed
86%

Scan complete. Ready to optimize.

Total Space Saved: 42.8 MB

Support open source original creation. Create sustainable, high-tech plugins.
Buy me a coffee to keep this project alive! ☕ Buy me a coffee

WebP Quality
Recommended: 82. Range: 50-100.
Max Resolution (px)
Images larger than this will be downscaled.
Allow Oversized Images
First N Direct Load
Number of top-of-page images to load without lazy loading. The most effective fix for LCP warnings. Start with 5 and tune for your layout.
Conversion Scope
Image Types to Convert
📋 Format Support Notes: ✅ JPEG/JPG → WebP: Fully supported. Best compression results.
✅ PNG → WebP: Fully supported. Transparent background is preserved.
⚠️ GIF → WebP: Static GIF only. Animated GIFs will become static (first frame only).
❌ HEIC / HEIF: Not supported. Convert to JPEG before upload.
❌ AVIF: Not supported. GD library does not handle AVIF.
❌ SVG: Not supported. SVG is a vector format.
✅ WebP: Already WebP. No conversion needed.
Smart Lazy Load
Images load with 1x1 placeholder, then 3 concurrent requests via a smart queue.
Global <picture> Wrapper

What does this do?

Wraps every image in a <picture> tag and adds a WebP <source>. Browsers automatically load the WebP version if supported.

Recommended: Always keep enabled for maximum browser compatibility.

Technical Details:
  • Works with both <img> and existing <picture> tags
  • Supports srcset for responsive images
  • Graceful fallback for browsers without WebP support
  • Compatible with Elementor, Gutenberg, WPBakery, etc.
Progressive Loading

What does this do?

Generates a tiny placeholder (12px max, 3-6KB) that loads instantly, then smoothly transitions to the full-quality WebP in under 500ms.

Recommended: Always keep enabled. Improves perceived performance and helps achieve better Core Web Vitals (LCP, CLS).

How it improves loading experience:
  • Users see a blurry but recognizable preview instantly
  • Blur to sharp transition in under 500ms
  • Reduces perceived loading time by up to 60%
  • Improves Largest Contentful Paint (LCP) scores
  • Prevents Cumulative Layout Shift (CLS) with fixed dimensions
Note: Creates a small .lqip.webp file (about 3-6KB) per image. Works best with JPEG and PNG. Disable only if you have very limited storage or thousands of images.
External Images
May affect performance for large external images.
Image Deletion Mode
Note: These options only apply to images deleted from WordPress Media Library. Manual FTP deletions are not affected.

🔄 Reset Options

Preview Size Original WebP Actions
hero-banner.jpg 1920×1080 2.36 MB 306.58 KB -87.3% Edit Reoptimize Remove Copy URL
product-showcase.png 980×980 608.15 KB 174.36 KB -71.3% Edit Reoptimize Remove Copy URL
team-photo.jpg 864×1247 1.82 MB 412.50 KB -77.3% Edit Reoptimize Remove Copy URL
icon-avatar.webp 128×128 8.12 KB Already WebP Remove
gallery-image-1.png 1536×864 795.83 KB Pending -
gallery-image-2.png 768×1108 1.05 MB Pending -
animated-banner.gif 600×400 1.24 MB Failed
Animated GIF not supported
 Retry Remove
1 of 3 156 items

Install in 60 Seconds

1

📥 Download

Get the ZIP file from our plugin page or GitHub.

2

⬆️ Upload

Upload via WordPress Plugins, Add New, Upload Plugin.

3

🚀 Optimize

Activate and click "Start Optimization" on the dashboard.

Frequently Asked Questions

Everything you need to know about Jacker OneWebP.

Does this work with animated GIFs?

No. The GD library used for conversion does not support animated GIF conversion. Animated GIFs will be skipped and marked as failed.

Will this slow down my site?

The conversion process runs in the background via AJAX. Frontend lazy loading ensures optimal performance for your visitors.

What happens to my original images?

Original images are preserved unless you enable the "Delete Original After Conversion" option in settings.

Does this work with WooCommerce?

Yes. Jacker OneWebP converts all product images and thumbnails automatically. Works perfectly with WooCommerce.

Is this really 100% free?

Yes. Jacker OneWebP is completely free, open-source (GPL-2.0+), and will always be free. No hidden costs, no premium versions.

What is First N Direct Load?

It controls how many top-of-page images skip lazy loading and get fetchpriority="high". This is the most effective way to fix LCP warnings from page builders. The optimal value is different for every site.

What is Progressive Loading?

Jacker OneWebP generates a tiny placeholder (12px, 3-6KB) that loads instantly, then smoothly transitions to the full-quality WebP in under 500ms. This dramatically improves perceived performance and LCP scores.

Does it work with Jacker CSS Merges Manager?

Yes. JCSSMM auto-detects Jacker OneWebP. When active, it rewrites background-image URLs inside merged CSS to point at the .jo.webp files Jacker OneWebP generated. Both plugins work independently.

Support Open Source

Jacker OneWebP is built with passion. If it helps your business, consider supporting sustainable development.