Cloudflare Images requires you to pre-define "variants" in the dashboard before you can use them. Need a 800x600 crop? Go to the dashboard, create a variant, name it, then reference it in your URL like imagedelivery.net/<account_hash>/<image_id>/my-variant. Every time you need a new size or quality combination, you're back in the dashboard. It's a configure → register → use flow.
img-src.io lets you specify transformations directly in the URL query string — no pre-registration needed. img-src.io/i/john/photo.webp?w=800&h=600&q=85&fit=cover just works on the first request. You can freely combine 20+ parameters (blur, sharpen, rotate, grayscale, etc.) without touching any dashboard. It's an upload → use flow.
We do offer presets (?p:thumbnail) which work similarly to Cloudflare's variants — named parameter sets you can reuse across URLs. The difference is that presets are optional and managed via API, not a prerequisite. You can go ad-hoc when prototyping and introduce presets later when your transformation needs stabilize, rather than being forced to define every combination upfront in a dashboard.