Does Cloudflare Polish Replace an Image Optimization Plugin?

If your site runs through Cloudflare, you’ve probably noticed the Polish setting in your dashboard. One click, and Cloudflare starts compressing your images. So it’s a fair question: if Cloudflare already does that, does Polish replace an image optimization plugin?

The short answer: no, it doesn’t.

The longer answer is that Polish and a dedicated optimizer like ShortPixel work on completely different layers. Polish recompresses copies of your images in Cloudflare’s cache, with a couple of settings. ShortPixel optimizes the actual image files on your server, using its own compression technology and giving you far more control over the result. That difference affects everything from file sizes to what happens the day you change plans or providers.

We went through Cloudflare’s own documentation to see what Polish does, where it stops, and how it fits next to an image optimization plugin. Here’s what we found.

What Cloudflare Polish actually does

Polish is Cloudflare’s one-click image optimization feature. When an image is fetched from your origin server, Cloudflare optimizes it in its cache, and every request after that gets the smaller version. Your image URLs stay the same, and you don’t need to change anything in your pages.

It comes with two compression modes:

• Lossless keeps the pixels identical, removes most metadata such as EXIF data, and recompresses the image data. JPEGs may be converted to progressive format.
• Lossy compresses harder, at the cost of a small loss in quality. It mainly affects JPEGs, but PNGs can also be compressed lossily or converted to JPEG when that saves more.

On top of that, an optional WebP setting creates WebP versions of your JPEG and PNG images and serves them to browsers that support the format, but only when the WebP file is significantly smaller.

Polish is available on Cloudflare’s Pro, Business, and Enterprise plans. It isn’t included in the Free plan.

And if your site is hosted on Kinsta or WP Engine, you may already be using it without knowing. The built-in image optimization both hosts offer at the CDN level is powered by Cloudflare Polish.

For what it is, Polish is genuinely convenient. The catch is in what it isn’t.

Where Polish stops

It optimizes copies, not your images

Polish works on the copy of each image stored in Cloudflare’s cache. The files on your server stay exactly as they were uploaded, so they aren’t optimized.

That has a few consequences:

• The image files on your origin server remain untouched by Polish.
• The optimization only exists while Polish is switched on and your images pass through Cloudflare’s cache. Switch to the Free plan, turn Polish off, or move to a different CDN, and your visitors get the original unoptimized files again once the cached copies expire.
• Server settings can quietly get in the way. According to Cloudflare, Polish may not be applied when your server sends a Vary header other than Vary: Accept-Encoding, or when an image isn’t cacheable.

It doesn’t resize anything

A 5,000-pixel photo straight from a phone stays 5,000 pixels wide after Polish. It’s recompressed, not resized.

In fact, Polish may not process it at all. Cloudflare recommends keeping images under 4,000 pixels in any dimension and under 20 MB, and images that are too large or complex are simply flagged as too large to process.

WebP only, no AVIF

Polish only converts images to WebP. AVIF isn’t part of Polish at all. Cloudflare offers it through its separate image transformations service, and Polish isn’t applied to images delivered that way.

There’s one more gap: if your server already serves WebP images, Polish won’t convert them and won’t optimize them either.

Two settings, very little control

Lossy or lossless, WebP on or off. That’s the full list of options. There’s no middle ground between the two compression modes, no resizing, and nothing for PDF files.

What an image optimization plugin does differently

A dedicated image optimizer like ShortPixel Image Optimizer doesn’t just flip a compression switch. Here’s what changes.

Its own compression technology

Many image compression tools rely on lowering the quality to a fixed value. That’s fast, but it tends to leave some images over-compressed and others heavier than they need to be. ShortPixel uses its own SmartCompress technology to find a better balance between file size and visual quality than simply applying a fixed quality setting.

SmartCompress is built on advanced algorithms, including SSIM (structural similarity index), which measures how closely the compressed image matches the original. Each image can go through multiple optimization passes to find a smaller result while preserving the target visual quality.

The difference shows up in the numbers. In our own test, simply lowering the quality factor reduced an image’s file size by about 10%. SmartCompress with the Glossy level reduced the same image by almost 47%, and the result was still visually identical to the original.

Three compression levels instead of two

ShortPixel gives you Lossy, Glossy, and Lossless. Glossy sits in between: it’s designed for photographers and online stores, where image quality matters more than squeezing out every last kilobyte.

WebP and AVIF, with fallbacks

ShortPixel can generate both WebP and AVIF versions from your JPEG, PNG, and GIF source images. When one of ShortPixel’s delivery methods is enabled, compatible browsers can receive those next-gen versions while the original format remains available as a fallback.

And if the resulting WebP or AVIF file is more than 5% larger than the compressed JPEG or PNG counterpart, ShortPixel drops it rather than storing a heavier version.

Optimized files, not optimized copies

ShortPixel optimizes the actual files on your server, including the WordPress thumbnail sizes you’ve selected for optimization. The optimized images are what your site serves, no matter which CDN or hosting provider sits in front of it, and they stay optimized if you move.

With backups enabled, which is the default, ShortPixel keeps the original files in a separate backup folder, so you can restore or re-optimize them later if needed.

Resizing, PDFs, AI Image SEO and bulk optimization

ShortPixel can automatically resize oversized uploads when you enable the resize option, so that 5,000-pixel phone photo doesn’t have to make it to your page at full size. It also optimizes PDF files and can bulk-optimize your entire existing Media Library in the background. It can also generate SEO data for all your images using AI which will improve your website’s SEO and visibility in search engines.

Cloudflare Polish vs. ShortPixel at a glance

Feature	Cloudflare Polish	ShortPixel Image Optimizer
What gets optimized	Copies in Cloudflare’s cache	Image files on your server
Compression	Lossy or Lossless	Lossy, Glossy, or Lossless
Next-gen formats	WebP	WebP and AVIF
Resizing	No	Yes
PDF optimization	No	Yes
Bulk Media Library optimization	No	Yes
AI Image SEO	No	Yes
Cloudflare plan needed	Pro or higher	None
If you disable it or switch CDN	Origin files remain unchanged	Optimized files stay with your site

Can you use Polish and ShortPixel together?

You can run ShortPixel on a site that uses Cloudflare, and plenty of sites do. But there’s little point in stacking Polish’s compression on top.

Cloudflare itself warns that a built-in image optimizer on your server or CMS may interfere with Polish, and that applying lossy optimization twice degrades quality more than it reduces file size. When an image is already fully optimized at the origin, Polish simply reports that no compression was needed.

So our recommendation is straightforward: let ShortPixel handle compression and next-gen formats, and switch Polish off.

So, does Polish replace an image optimization plugin?

Polish is a convenient way to get some compression at the edge with almost no setup, and it’s better than nothing if your images aren’t optimized at all.

But it recompresses copies instead of files, it only works while it’s switched on, it stops at WebP, it only works on Cloudflare’s more expensive plans and it gives you two settings to work with. ShortPixel goes further with its own SmartCompress technology, giving you more control over compression, quality, formats, resizing, and the files themselves. And the results stay with your site wherever it goes.

If you already use ShortPixel, you don’t need Polish. If you only use Polish, your images are optimized for exactly as long as Cloudflare keeps doing it for you.

Curious how your own images compare? Run a few through our free online image compressor, or install ShortPixel Image Optimizer and start with 100 free credits every month.

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