If your site serves more than a handful of images, there comes a point where optimizing them one by one stops scaling. Manually compressing a hero image with a tool like our image compressor is perfect for a landing page or a blog post. But when you have hundreds of product photos, user uploads, or a CMS full of editors who export 8 MB PNGs, you want the optimization to happen automatically. That is the job of an image CDN.

What an image CDN actually does

An image CDN sits between your original images and your visitors. Instead of serving the file you uploaded, it serves a version generated on the fly: resized to the exact dimensions the page needs, converted to a modern format like WebP or AVIF when the browser supports it, compressed to a sensible quality, and cached on servers close to the visitor. One original file in, dozens of optimized variants out — with no build step and no manual work.

The result is usually a 40–70% reduction in image bytes compared to serving originals, which directly improves Largest Contentful Paint. If you want the background on why formats matter so much, read our guide to JPG vs WebP vs AVIF.

The four we would actually recommend

Cloudinary — most complete platform

Cloudinary is the most feature-rich option: URL-based transformations, automatic format and quality selection (f_auto/q_auto), video support, and a large plugin ecosystem for every major CMS and framework. The free tier (25 monthly credits, roughly 25 GB of bandwidth or 25k transformations) genuinely covers small sites. The trade-off is pricing complexity — past the free tier, credits take some spreadsheet work to predict, and heavy-traffic sites can find it expensive.

ImageKit — best price/performance for most sites

ImageKit covers the same core ground — real-time resizing, automatic WebP/AVIF, a media library — with simpler, bandwidth-based pricing and a 20 GB free tier. It can also sit in front of your existing storage (S3, your own server), so adopting it is usually a DNS change and a URL prefix, not a migration. For most small-to-medium sites this is the option we would try first.

Bunny Optimizer — cheapest flat rate

Bunny.net takes a different approach: its Optimizer is a flat-fee add-on (around $9.5/month) on top of its very cheap CDN bandwidth. You get automatic WebP conversion, resizing, and compression without per-transformation pricing. It has fewer bells and whistles — no fancy media library, fewer transformation options — but if your need is “make my existing images fast without surprises on the invoice,” it is hard to beat.

Cloudflare Images — simplest if you are already on Cloudflare

If your DNS already runs through Cloudflare, Cloudflare Images (and the Polish/Image Resizing features on paid plans) adds optimization with almost zero setup. Pricing is straightforward ($5/month per 100k images stored, $1 per 100k transformations). The transformation options are more limited than Cloudinary or ImageKit, but the operational simplicity is unmatched for teams already in the ecosystem.

How to choose

  • Small site, first CDN: ImageKit — generous free tier, simple pricing, no migration.
  • Media-heavy product, user uploads, video: Cloudinary — the feature depth pays off.
  • Cost-sensitive, predictable bills: Bunny Optimizer — flat fee, cheap bandwidth.
  • Already on Cloudflare: Cloudflare Images — least new infrastructure.

Gotchas to check before you commit

  • Transformation pricing at scale. A page with ten images at four responsive sizes each is forty transformations per unique visitor cache-miss. Estimate with your real traffic before trusting any free-tier math.
  • Cache invalidation. If editors overwrite images while keeping the same filename, confirm how quickly the CDN picks up the change — some cache aggressively and need versioned URLs.
  • Vendor lock-in. Prefer setups that proxy your existing storage (ImageKit and Bunny both can) over ones that require migrating your media library into the vendor's bucket. Leaving is much easier when your originals stayed where they were.
  • Check the output yourself. Auto-quality settings occasionally over-compress detailed images. Spot-check your most important pages after enabling any “auto” mode.

Do you even need one?

Honestly — not always. If your site has a few dozen static images that rarely change, a one-time manual pass gets you the same bytes for free: run your images through our website image optimizer, convert them to AVIF or WebP, and serve them from your existing host. An image CDN earns its fee when images are numerous, frequently changing, or uploaded by people who will never open an optimizer. Start manual, and add the CDN when the manual work becomes the bottleneck.