WordPress Image Optimizer Plugins: Free Tiers Compared

WordPress core resizes every upload and serves the right size per screen, but it has never compressed those files and it does not convert them to WebP or AVIF, so a WordPress image optimizer plugin is still doing real work. The free pick is Converter for Media, which converts to WebP on your own server with no monthly cap and no account, and holds 4.9 out of 5 from 1,099 reviews across 500,000+ installs. If you would rather pay for a hands-off service, Imagify at $4.99 a month billed yearly adds AVIF and covers roughly 5,000 images a month. Check the unit each vendor counts in before you compare prices: ShortPixel’s 100 free credits a month covers seven photos on a default WordPress install, not a hundred.

Jump to: what core already does · what happens if you stop paying · which one fits you · the comparison · the plugins · WooCommerce stores · images already uploaded · the verdict · questions

Does WordPress optimise images on its own?

Half of it, yes. Since WordPress 5.3 core scales any upload wider or taller than 2560 pixels down to that threshold and uses the scaled file as the largest available size. It also generates six sub-sizes for every photo — thumbnail at 150×150, medium at 300×300, medium_large at 768 wide, large at 1024×1024, and the 1536×1536 and 2048×2048 sizes added in 5.3 — and writes them into a srcset so a phone never downloads the desktop file.

The other half it does not touch. Core does not recompress anything. It accepts WebP uploads and, since WordPress 6.5, AVIF uploads too, but it will not convert your JPEGs to either format on its own: that needs the image_editor_output_format filter, which is a developer opt-in rather than a default. Core also always preserves the file you uploaded, so nothing it does is destructive.

That is the whole case for this category. You are buying compression and format conversion, not resizing, and any plugin whose pitch is “creates multiple sizes for every screen” is selling you something core has done for years.

Check two things before installing anything. If you run a caching plugin the optimiser may already be in it: LiteSpeed Cache, at 7 million+ installs and 4.8 out of 5 from 2,770 reviews, carries Image Optimization with lossless, lossy, AVIF and WebP handling through QUIC.cloud, free up to a usage tier. Its own FAQ notes that nothing is optimised unless Auto Request Cron is switched on, so it can sit installed and idle. WPNeon runs LiteSpeed Cache.

And the WordPress Performance Team publishes Modern Image Formats (version 2.7.1, updated in August 2026, 100,000+ installs), which generates WebP or AVIF sub-sizes at upload on your own server, free. Its 3.5 out of 5 from 25 reviews is explained by its own documentation: by default it replaces the JPEG sub-sizes rather than adding to them, so unless you switch on Output fallback images, a browser without AVIF support has nothing to fall back to.

What happens to your images if you stop paying?

This is the question the category avoids, and it splits these plugins in two.

Plugins that write optimised files into your site keep working after you leave. Converter for Media writes WebP copies into /wp-content/uploads-webpc/ and states plainly that it “does not modify your original images in any way”. EWWW replaces a library file only if the optimised version is smaller, and keeps local backups. Imagify and ShortPixel both write their WebP and AVIF files to your server and back up the originals. TinyPNG and reSmush.it send images to a cloud to be squeezed and put the results back on your server. Cancel any of these and every image you already processed stays where it is.

Plugins that serve images from the vendor’s cloud do not. Optimole rewrites every image URL on your site to its own CloudFront network. Nothing optimised is ever written into your media library, so the day the account stops, you are back to the unprocessed originals you started with. Optimole’s documentation is unusually honest about the free-plan edge: exceed the allowance and “Optimole will return your original images and permanently deactivate your account’s optimized image delivery”. On a paid plan the opposite happens — it “will automatically upgrade your subscription to the next plan tier”, which is a bill rather than a breakage. And if you have used the Cloud Library to offload originals off your server to save disk space, leaving is no longer a matter of switching a plugin off.

Smush, ShortPixel and EWWW all offer a CDN as an option rather than the architecture. The rule is the same for all of them: whatever is delivered only from the vendor’s network leaves with the vendor.

Which WordPress image optimizer plugin fits your site?

Three answers decide this, and none of them is “which plugin is best”. What kind of images you have decides whether a file-size cap will bite. Whether you will let a third party serve your images decides what you are left with if you stop. And free-only rules out the two formats that actually save the most.

Install counts, ratings and free-tier limits read from each plugin’s WordPress.org page and each vendor’s own pricing or documentation page on 17 September 2026.

The comparison: what each free tier is really worth

Every vendor on this page calls its entry plan free, and they measure it in four different units: images, megabytes, credits and visitors. The fourth column converts all of them into the same thing — how many photos a month you can actually put through, once WordPress’s own sub-sizes are counted.

Figures read from each plugin’s WordPress.org page and each vendor’s own pricing or documentation page on 17 September 2026. The fourth column is calculated, not quoted.

How that fourth column is worked out. A photo uploaded to a default WordPress install does not become one file. Core scales anything over 2560 pixels and then generates six sub-sizes, so you have seven files before any plugin touches them. ShortPixel’s own documentation states that “1 credit = 1 image or thumbnail” and that each WebP copy costs a credit too, and its worked example charges 18 credits for a single image with eight thumbnails. Seven files plus seven WebP copies is 14 credits, so 100 free credits a month is seven photos, not a hundred. On a WooCommerce store, where three more sub-sizes are registered, it is ten files, 20 credits, and five product photos a month.

TinyPNG does the same arithmetic in public and reaches the same shape: its 500 free credits are “roughly 100 images per month”, and “with the conversion feature enabled, you can roughly compress and convert 50 images per month for free”. Imagify counts megabytes instead and puts its 20 MB at about 200 images. The uncapped local plugins do not count at all.

The spread between the highest and lowest free tier on this page is therefore not a few per cent. It is seven photos a month against unlimited, between products that use the same word.

The plugins, verified

Converter for Media

For anyone who wants WebP for free without an account or a counter. Version 6.6.5, updated in August 2026, 500,000+ active installs, 4.9 out of 5 from 1,099 reviews, tested up to WordPress 7.1, requires PHP 7.4.

It converts on your own server and writes output to a directory of its own, stating that it “does not modify your original images in any way”; optimisation can be undone per image. Delivery follows a fallback chain — AVIF, then WebP, then the original format — so nothing breaks on an old browser. One-click bulk conversion handles the existing library and new uploads convert automatically.

The limitation is the free boundary. AVIF is a Pro feature, and the vendor’s own figure is that AVIF files weigh about half what WebP files do, so the free version leaves a real saving on the table. Conversion also costs your server CPU rather than a vendor’s.

Converter for Media on WordPress.org

EWWW Image Optimizer

For large files and libraries with no monthly ceiling. Version 8.7.7, updated in September 2026, 1 million+ active installs, 4.8 out of 5 from 1,839 reviews, tested up to WordPress 7.1, requires PHP 7.4.

The free tier runs jpegtran, optipng, pngquant, gifsicle and cwebp on your own host and offers “unlimited image optimization to compress images of any size” — the only plugin here with no count limit and no file-size limit at once. WebP conversion is free, with the listing citing 60 percent average savings. If your host blocks PHP’s exec(), EWWW falls back to unlimited lossless JPEG optimisation and WebP conversion through its own API at no charge.

The limitation is that AVIF is only available through the paid Easy IO CDN, which puts delivery in the vendor’s hands. The settings screen is also the densest here.

EWWW Image Optimizer on WordPress.org

Imagify

For a site that wants WebP and AVIF without running anything locally. Version 2.3.4, updated in September 2026, 1 million+ active installs, 4.3 out of 5 from 1,654 reviews, tested up to WordPress 7.1, requires PHP 7.4.

It is the only cloud plugin here that includes both modern formats on its free plan rather than gating them, and it serves the results from your own server with an automatic JPEG or PNG fallback when a browser supports neither. Originals go to a backup folder for one-click restore, so the compression level is reversible. Pricing is in megabytes: 20 MB a month free at roughly 200 images, Growth at 500 MB for $4.99 a month billed yearly — $59.88 a year, roughly 5,000 images — with overage at $5 per additional gigabyte, and Infinite at $9.99 a month billed yearly, $119.88 a year.

The limitation is its reputation. At 4.3 out of 5 it is the lowest-rated maintained plugin here, with 222 one-star reviews against 1,293 five-star, a wider split than any other plugin on this page.

Imagify on WordPress.org

ShortPixel Image Optimizer

For photographers who want compression they can reverse. Version 6.5.6, updated in September 2026, 300,000+ active installs, 4.5 out of 5 from 819 reviews, tested up to WordPress 7.1, requires PHP 7.4.

It converts JPEG, PNG and GIF to WebP and AVIF, writes both locally, and offers a built-in CDN as an option rather than a requirement. The feature that separates it is the backup model: originals are kept, so you can restore an image or move it between lossy, glossy and lossless without re-uploading, and Smart Backups saves disk space by backing up only the main files. Glossy is a compression level aimed squarely at photographic work.

The limitation is the pricing unit, and it is the sharpest on this page. A credit is one image or one thumbnail, WebP and AVIF copies each cost one more, and the vendor’s own example spends 18 credits on a single upload. Treat the 100-credit free tier as a trial, not a plan.

ShortPixel Image Optimizer on WordPress.org

Optimole

For image-heavy sites willing to hand delivery to a CDN. Version 4.2.13, updated on 14 September 2026, 200,000+ active installs, 4.7 out of 5 from 639 reviews, tested up to WordPress 7.1, requires PHP 7.4.

It rewrites every image URL to a CloudFront network with 450+ locations and serves WebP or AVIF at dimensions matched to the requesting device rather than to whichever sub-size WordPress generated at upload. That per-device sizing is the thing no local plugin can do. Its free plan puts no cap on images at all: it meters 2,000 visits a month, counted as unique daily users, and paid tiers begin at 48,000.

The limitation is what the architecture costs you. Nothing optimised is written into your library, so the optimisation ends when the account does. Exceed the free plan and Optimole “will return your original images and permanently deactivate your account’s optimized image delivery”; exceed a paid plan and it upgrades your subscription to the next tier automatically.

Optimole Affiliate link · Optimole on WordPress.org

Smush

For the least-effort free compression on a site with ordinary photos. Version 4.3.3, updated on 16 September 2026, 1 million+ active installs, 4.8 out of 5 from 6,051 reviews, tested up to WordPress 7.1, requires WordPress 6.4 and PHP 7.4.

It is the most-reviewed plugin in this category by a wide margin and the easiest to set up, and it bundles a lazy loader so you are not running two plugins for two jobs.

The limitation is how much of it is paid. The free version skips any image over 5 MB, where Pro handles up to 256 MB, and neither WebP nor AVIF is available free: local WebP conversion is documented by the vendor as a Smush Pro feature, as is the 119-node CDN. So the most popular plugin here is the one that does least of what this page is about unless you pay. Pro runs $36 a year for one site at the rate shown on the vendor’s page, rising to $60 for three and $120 for ten.

Smush Pro Affiliate link · Smush on WordPress.org

TinyPNG

For anyone who wants to know the exact price of a bulk run before starting it. Version 3.8.0, updated in August 2026, 100,000+ active installs, 4.5 out of 5 from 177 reviews, tested up to WordPress 7.1.

It handles AVIF, WebP, PNG, animated PNG and JPEG through the Tinify API, and it is the only vendor here that publishes a per-unit rate instead of a plan: the first 500 compressions a month are free, the next 9,500 cost $0.009 each and the following 10,000 cost $0.002 each. That makes a one-off library migration costable in advance, and you choose which thumbnail sizes to include, which is how you control the bill.

The limitation is the same credit trap as ShortPixel, more gently priced. The vendor’s own figure is that 500 free credits is roughly 100 images, halving to 50 once WebP or AVIF conversion is switched on, because conversion costs an extra credit per size.

TinyPNG on WordPress.org

reSmush.it

For a personal blog that wants compression and nothing else. Version 1.0.6, updated in August 2026, 100,000+ active installs, 4.3 out of 5 from 165 reviews, tested up to WordPress 7.1.

There is no account, no key and no counter: it posts images to a free API, gets smaller ones back and writes them to your server, with bulk optimisation for the existing library and per-image exclusions. For a hobby site with modest photos it is the shortest path from installed to done.

The limitations are two and both are hard. Files over 5 MB are rejected outright, and the API’s own terms make the free service personal use only, directing commercial and business users to a paid arrangement. A shop, a client site or anything that earns money should not be running on it.

reSmush.it on WordPress.org

Skip these. Image Optimizer by 10Web, formerly the WebDorado plugin that older roundups still recommend, was last updated in 2024, is tested only to WordPress 6.7.7 and carries the directory’s warning that it “hasn’t been tested with the latest 3 major releases of WordPress”; it is down to 3,000+ active installs. PB SEO Friendly Images was closed on WordPress.org on 27 July 2023 for a security issue and cannot be downloaded. Optimus is still listed at version 1.6.3 but was last updated in April 2026 and is tested only to WordPress 6.9.7, with 10 of its 69 reviews at one star — there is no reason to choose it over EWWW or Converter for Media.

What is different about WooCommerce image optimization?

A store is not a blog with more pictures. WooCommerce registers three sub-sizes of its own on top of core’s six — woocommerce_thumbnail for shop grids, woocommerce_single for product pages and woocommerce_gallery_thumbnail for the gallery switcher — so a product photo becomes ten files instead of seven. Multiply that by a catalogue and by gallery images per product, and the arithmetic changes which plugin is correct.

Anything priced per image or per thumbnail is the wrong shape. Ten files plus ten WebP copies is 20 ShortPixel credits per product photo. A thousand product photos is 20,000 credits before you have added a single gallery shot, and the free tier covers five. TinyPNG’s published rate makes the same job costable but not cheap.

Two units survive contact with a catalogue. Megabytes, because a product photo is small even when there are thousands of them: Imagify’s Infinite plan at $119.88 a year removes the counter entirely. Or visits, because traffic and catalogue size are independent: Optimole prices on unique daily users, so adding 5,000 SKUs costs nothing extra. Free and local is the third answer, with Converter for Media or EWWW working on your own server for nothing, at the cost of CPU time best spent in batches.

One more store-specific point: set your WooCommerce image dimensions in the Customizer before you bulk-optimise, not after. Change them afterwards and WordPress regenerates every sub-size, which means paying to optimise the same catalogue twice.

What about the images already in your library?

Most people arrive with a few thousand images already uploaded, and every plugin above has a bulk tool for that. Four things, in order.

1. Take a backup first. Compression that overwrites files is the one step on this page you cannot undo from inside WordPress if the plugin has no restore. Converter for Media never touches originals, and EWWW, Imagify and ShortPixel keep backups; check which of those applies to the one you chose before you start.
2. Fix your image sizes before the bulk run, not after. Media Settings and, on a store, the Customizer decide how many sub-sizes exist. Changing them later regenerates everything and costs you the run a second time.
3. Decide which sub-sizes to optimise. On a credit-priced plugin this is the single biggest lever on the bill, and both ShortPixel and TinyPNG let you exclude sizes your theme never actually serves.
4. Run it in batches. A local converter uses your own CPU and a cloud plugin makes one API call per file, so a library of several thousand images is a job for several sessions rather than one. Hosts that cap CPU time will kill a single long run.

Compression alone rarely fixes a slow page on its own. If images are still the bottleneck after a bulk run, the next lever is when they load rather than what they weigh.

Which WordPress image optimizer plugin should you choose?

For most people, Converter for Media. It converts to WebP on your own server with no cap, no account and no credit counter, it never alters your originals, and at 4.9 out of 5 from 1,099 reviews it is the best-regarded plugin in the category. If your photos are large or you want compression as well as conversion, EWWW does the same job locally with no file-size limit.

If you will pay a little, Imagify at $59.88 a year. It is the only cloud plugin here that puts WebP and AVIF on the free plan rather than behind the paywall, it serves from your own server with a proper fallback, and it prices in megabytes so the bill does not scale with your thumbnail count. For a store, its Infinite plan at $119.88 a year is the version that makes sense.

Check your cache plugin before you install anything. LiteSpeed Cache already includes image optimisation, and its own FAQ notes it does nothing until Auto Request Cron is switched on — a free optimiser sitting idle on 7 million sites.

Skip the 10Web plugin and PB SEO Friendly Images, which older roundups still list and which are stale and closed respectively. Treat ShortPixel’s free tier as a trial rather than a plan, and do not put a commercial site on reSmush.it, whose free service is licensed for personal use only.

Once you have chosen

• WordPress lazy load plugins — once the files are smaller, the next gain is not loading the ones nobody scrolls to, and core may already be doing it.
• Change WordPress featured image size — do this before a bulk run, because changing sizes afterwards regenerates every sub-size and costs the run twice.
• WordPress cache plugins — several bundle image optimisation, so check here before paying a second vendor for it.
• Must-have WooCommerce plugins — if the store is the reason you are here, the rest of the stack that decides its speed.

Frequently asked questions

Does WordPress optimise images automatically?

Only partly. Since WordPress 5.3 core scales uploads wider or taller than 2560 pixels down to that threshold and generates six sub-sizes for every photo, served through a srcset so phones get small files. It does not recompress anything and it does not convert to WebP or AVIF on its own. Core accepts WebP and, since 6.5, AVIF uploads, but converting your existing JPEGs needs a filter or a plugin.

What is the best free WordPress image optimizer plugin?

Converter for Media for most sites. It converts images to WebP on your own server with no monthly cap, no credits and no account, writes the output to a separate folder without altering your originals, and holds 4.9 out of 5 from 1,099 reviews across 500,000+ installs. For large files, EWWW Image Optimizer is free with no count limit and no file-size limit, and includes WebP conversion at no cost.

How many images does ShortPixel’s free plan actually cover?

About seven photos a month on a default WordPress install. ShortPixel defines one credit as one image or one thumbnail, and each WebP copy costs a credit too. Core generates six sub-sizes plus a scaled original, so one photo is seven files and about 14 credits with WebP. On a WooCommerce store, where three more sub-sizes exist, it is 20 credits and five product photos.

Do I lose my optimised images if I cancel the plugin?

It depends on where the files live. Converter for Media, EWWW, Imagify, ShortPixel, TinyPNG and reSmush.it all write optimised files onto your own server, so cancelling changes nothing for images already processed. Optimole serves everything from its own CDN and writes nothing into your media library, so ending that account returns you to your original unoptimised images.

Which image optimizer is best for a WooCommerce store?

One priced in megabytes or visits, not in credits. WooCommerce registers three sub-sizes on top of core’s six, so each product photo is ten files and roughly 20 credits once WebP copies are counted. Imagify’s Infinite plan at $119.88 a year removes the counter, and Optimole prices on unique daily visitors so catalogue size does not affect the bill. Free and local, Converter for Media or EWWW cost nothing.

Is WebP or AVIF better for WordPress images?

AVIF files are smaller, by about half again on the vendor figures Converter for Media publishes, but WebP has wider support and is what most free tiers give you. The practical answer is to serve AVIF where the browser accepts it, WebP next and the original JPEG or PNG as a fallback. Imagify, ShortPixel, Optimole and Modern Image Formats all do both; Smush free does neither.