Most image CDN pricing looks cheap until traffic shows up. The line item that gets you isn't storage or transforms — it's egress, the fee per gigabyte delivered to your users. Understanding it is the difference between a predictable bill and a surprise four-figure one.
What egress is
Every time someone loads one of your images, those bytes leave the provider's network — that's egress. Traditional clouds and many CDNs meter it per GB. A 300 KB image served a million times is 300 GB of egress; at typical rates that's real money, and it scales with your success, not your effort.
Why it's dangerous
- Virality is a liability. A post that takes off multiplies egress overnight — exactly when you can least afford a surprise.
- It's hard to predict. You're billed on other people's behavior (views), not yours (uploads).
- It compounds with hotlinking. Embeds on other sites drive views you don't control.
Why flat delivery pricing is possible
Some delivery models don't charge per byte served, so the scary, unpredictable bandwidth line item disappears — serving an image a million more times doesn't change the bill. That's how swiftimg keeps pricing flat: plans are flat with usage-based overage on storage and transforms, not bandwidth, so your bill doesn't spike when a post takes off.
What to check before you commit
- Is bandwidth/egress metered? At what rate?
- Model your real view volume, not just uploads.
- Are transforms gated (signed URLs) so they can't be abused?
- Is delivery cached globally so repeat loads are instant?
See how the math compares against Cloudinary, imgix, and Bunny.net, or read the broader image CDN buyer's guide.