by Kraken.io 4.5 (119 reviews)

Kraken.io Image Optimizer – Compress, Convert to WebP & AVIF, Resize & Bulk Optimize

Name: Kraken.io Image Optimizer – Compress, Convert to WebP & AVIF, Resize & Bulk Optimize
Rating: 4.5 (119 reviews)
Author: Kraken.io

Optimize images automatically — compress, resize and convert to WebP, AVIF & more with Kraken.io. Faster pages, smaller files, same quality.

Kraken.io Image Optimizer ranks #1,573 among WordPress.org plugins with 10,000+ active installations, is #192 of 6,305 in the Media category, a 4.5/5 rating from 119 reviews, and was last updated Jun 22, 2026. Data from WordPress.org, refreshed twice daily — see methodology.

Tested up to WP 7 (Current: 7.1)

v3.0.3 Current Version v3.0.3

Updated 2 months ago Last Update on 22 Jun, 2026

Refreshed 13 hours ago Last Refreshed on

#192 of 6,305 in Media Top 5% by installs Downloads -16.3% this week

View on WordPress.org

Rank

#1,573

-3 this week

Active Installs

10K+

-44.7%

KW Avg Position

21.2

0.4 better

Downloads

398.4K

+80 today

Support Resolved

— No change

Rating

90%

Review 4.5 out of 5

4.5 (119 reviews)

Next Milestone 20K

Total Progress 81%

10K+ 20K+

152

Ranks to Climb

Growth Needed

8,000,000

Active Installs

Pro

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Need 1,898 more installs to reach 20K+

Rank Changes

Current #1,573

Change

Best #

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Active Installs Growth

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Active Installs 0,000,000+

Growth +0.0%

Peak 0,000,000

Downloads Growth

Downloads

Growth

Peak

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Reviews & Ratings

4.5

119 reviews

Overall 90%

100 (84%)

6 (5%)

1 (1%)

2 (2%)

10 (8%)

Security History

Source: WPVulnerability

3 known vulnerabilities on record · 0 in the last 24 months · checked 1 week ago

Feb 1, 2023

Kraken.io Image Optimizer – Compress, Convert to WebP & AVIF, Resize & Bulk Optimize [kraken-image-optimizer] < 2.7.0

CVE-2023-0619 · Fixed in v2.7.0
Jan 17, 2023

Kraken.io Image Optimizer – Compress, Convert to WebP & AVIF, Resize & Bulk Optimize [kraken-image-optimizer] < 2.6.8

CVE-2023-22708 · Fixed in v2.6.8
Sep 23, 2022

Kraken.io Image Optimizer – Compress, Convert to WebP & AVIF, Resize & Bulk Optimize [kraken-image-optimizer] < 2.6.6

CVE-2022-38454 · Fixed in v2.6.6

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Plugin Details

Version: 3.0.3
Last Updated: Jun 22, 2026
Requires WP: 4.9+
Tested Up To: 7
PHP Version: 5.6 or higher
Author: Kraken.io

Support & Rating

Rating: ★ ★ ★ ★ ★ 4.5
Reviews: 119
Support Threads: 0
Resolved: 0%

Keywords

AVIF compress images convert webp image optimization optimize images

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TL;DR

AI summary of the plugin's readme

This plugin is for WordPress site owners who want smaller, faster-loading images without manual work. It automatically compresses, resizes and converts uploaded images and thumbnails using the Kraken.io cloud API.

Compresses images automatically
Converts to WebP and AVIF
Intelligent lossy and lossless modes
Smart resizing of oversized uploads
Bulk optimize existing library
Optimizes PDF files
Media Library summary panel
Multisite support

Frequently Asked Questions

Common questions about Kraken.io Image Optimizer – Compress, Convert to WebP & AVIF, Resize & Bulk Optimize

With intelligent lossy mode (the default), Kraken.io recompresses each image to a quality level below the threshold of human perception — you'll find it very hard to tell the optimized image from the original, even up close, while saving well over half the file size. Prefer pixel-perfect results? Switch to lossless mode in the settings.

The plugin replaces each image file with its optimized version, so optimized images stay on your site permanently — even after you deactivate or uninstall the plugin. Nothing reverts. (Keep your own backups as you would for any media, especially before bulk-optimizing.)

Two ways: open Media → Bulk Optimize with Kraken.io and run Krak 'em all to process your whole library with live progress, or switch the Media Library to List view and click Optimize in the Kraken.io column for any individual image.

Set Convert uploads to (in the panel or under Settings → Kraken.io) to WebP or AVIF. New uploads are converted to that next-gen format and the smaller files are served to browsers that support them — exactly what Google PageSpeed's "Serve images in next-gen formats" audit asks for.

JPEG, PNG, animated GIF, WebP, AVIF, HEIC/HEIF and PDF.

SVG is XML that can carry inline scripts and event handlers, which makes raw SVG uploads a stored cross-site-scripting (XSS) risk. For your site's safety the plugin does not enable raw SVG uploads. (Kraken.io's API can optimize SVG; safe in-WordPress support requires a markup sanitizer and an explicit, high-trust opt-in, which is on the roadmap.)

Yes. A single API key and secret can be used across as many sites and blogs as you like, including multisite networks — there is no per-site license.

Yes. Images are uploaded to Kraken.io from your server rather than fetched by URL, so the plugin works on local, staging and unpublished installations, and behind firewalls or basic auth.

Kraken.io's focus is the precise balance between quality and file size: its intelligent lossy engine targets the greatest possible savings while keeping results indistinguishable from the original to the human eye. If you want maximum compression without ever having to eyeball the result against the source, this is the plugin for you — backed by a mature, standalone optimization service and API.

Yes — that's the point. Compressing every size, converting to WebP/AVIF and capping oversized uploads directly address Properly size images, Efficiently encode images, Serve images in next-gen formats and Largest Contentful Paint (LCP).