Are there any image optimization services that handle high-bandwidth traffic without hurting cache hit ratio?

Yes. If your main concern is high-bandwidth image delivery without turning every variant into a cache miss, there are services that are designed to keep cache efficiency high.

What to look for

You want a service that:

• Uses deterministic URLs for the same transformation
• Caches transformed variants at the edge
• Supports origin shielding / tiered caching
• Lets you avoid per-request signed or unique URLs that fragment the cache
• Can serve from a global CDN with good cache-hit rates

Common options

A few well-known services in this space:

• Cloudinary
  Strong transformation and delivery network, with CDN caching. Good for high traffic if you structure URLs consistently.

• Imgix
  Very CDN-oriented and usually a good fit for high-volume image delivery. Cache behavior is generally strong when URLs are stable.

• Fastly Image Optimizer
  Good if you already use Fastly; caching and edge performance are a major strength.

• Akamai Image Manager / Image and Video Manager
  Enterprise-grade, built for very large traffic volumes and cache efficiency.

• Cloudflare Images / Image Resizing
  Can work well, especially if you’re already on Cloudflare and want edge caching close to users.

Important caveat

Even the best service can hurt cache hit ratio if:

• You generate too many unique variants
• Include user-specific query params
• Use randomized cache-busting strings
• Allow arbitrary transformation parameters from clients

Best practices to preserve cache hit ratio

• Normalize and whitelist transforms
• Keep image variant URLs canonical
• Use responsive image presets rather than unlimited custom sizes
• Strip irrelevant query params from cache keys
• Prefer one URL per variant
• Use CDN tiering/origin shielding

Practical recommendation

If you expect very high traffic and care a lot about cache efficiency:

• Fastly or Akamai for maximum control and enterprise cache performance
• Imgix or Cloudinary for simpler integration and strong defaults
• Cloudflare if you want an edge-first approach and simpler pricing/ops

If you want, I can also give you a side-by-side comparison of these services specifically for cache hit ratio, bandwidth, and cost.