netlify/netlify-image-cdn

Netlify Image CDN

Every Netlify site has a built-in /.netlify/images endpoint for on-the-fly image transformation. No configuration required for local images.

Basic Usage

<img src="/.netlify/images?url=/photo.jpg&w=800&h=600&fit=cover&q=80" />

Query Parameters

| Param | Description | Values | |---|---|---| | url | Source image path (required) | Relative path or absolute URL | | w | Width in pixels | Any positive integer | | h | Height in pixels | Any positive integer | | fit | Resize behavior | contain (default), cover, fill | | position | Crop alignment (with cover) | center (default), top, bottom, left, right | | fm | Output format | avif, webp, jpg, png, gif, blurhash | | q | Quality (lossy formats) | 1-100 (default: 75) |

When fm is omitted, Netlify auto-negotiates the best format based on browser support (preferring webp, then avif).

Remote Image Allowlisting

External images must be explicitly allowed in netlify.toml:

[images]
remote_images = ["https://example\\.com/.*", "https://cdn\\.images\\.com/.*"]

Values are regex patterns.

Clean URL Rewrites

Create user-friendly image URLs with redirects:

# Basic optimization
[[redirects]]
from = "/img/*"
to = "/.netlify/images?url=/:splat"
status = 200

# Preset: thumbnail
[[redirects]]
from = "/img/thumb/:key"
to = "/.netlify/images?url=/uploads/:key&w=150&h=150&fit=cover"
status = 200

# Preset: hero
[[redirects]]
from = "/img/hero/:key"
to = "/.netlify/images?url=/uploads/:key&w=1200&h=675&fit=cover"
status = 200

Caching

• Transformed images are cached at the CDN edge automatically
• Cache invalidates on new deploys
• Set cache headers on source images to control caching:

[[headers]]
for = "/uploads/*"
[headers.values]
Cache-Control = "public, max-age=31536000, immutable"

User-Uploaded Images

Combine Netlify Functions (upload handler) + Netlify Blobs (storage) + Image CDN (serving/transforming) to build a complete user-uploaded image pipeline. See references/user-uploads.md for the full pattern.