External URL Image Transform#

Transform images from external URLs without uploading them to Snapkit. Fetch and process images from Slack profile pictures, external CDN images, and other sources with resizing, format conversion, and more.

Use Cases#

Slack/Discord Avatars: Convert profile images to optimized sizes and formats
External CDN Images: Transform images from other services to WebP/AVIF
Quick Image Processing: Test image transformations without uploading

URL Format#

Basic Format#

GET https://cdn.snapkit.studio/external?url={encodedExternalURL}&transform={parameters}

Important: The external URL in the url parameter must be URL-encoded. Without encoding, query parameters will not be parsed correctly.

Plan	CDN Domain
Standard	`cdn.snapkit.studio`
Enterprise	Custom domain (e.g., `cdn.yourcompany.com`)

Usage Examples#

Basic Transform (WebP)#

# Convert Slack avatar to WebP
# Original URL: https://ca.slack-edge.com/T04MAT2PXJ4-U0953CM4ZV3-ea508a85b199-512
curl "https://cdn.snapkit.studio/external?url=https%3A%2F%2Fca.slack-edge.com%2FT04MAT2PXJ4-U0953CM4ZV3-ea508a85b199-512&transform=format:webp"

Resize + Format Conversion#

# Resize to 800px width + AVIF conversion
# Original URL: https://example.com/photo.jpg
curl "https://cdn.snapkit.studio/external?url=https%3A%2F%2Fexample.com%2Fphoto.jpg&transform=w:800,format:avif,quality:85"

Complex Transform (Crop + Effects)#

# Square crop + grayscale
# Original URL: https://example.com/photo.jpg
curl "https://cdn.snapkit.studio/external?url=https%3A%2F%2Fexample.com%2Fphoto.jpg&transform=w:400,h:400,fit:cover,grayscale"

Enterprise Custom Domain#

# Enterprise customers use their own CDN domain
# Original URL: https://example.com/image.jpg
curl "https://cdn.yourcompany.com/external?url=https%3A%2F%2Fexample.com%2Fimage.jpg&transform=w:600,format:webp"

Transform Parameters#

External URL transforms support the same parameters as regular image transforms:

Parameter	Type	Description
`w`	number	Width (1-16384px)
`h`	number	Height (1-16384px)
`format`	string	jpeg, png, webp, avif, auto
`quality`	number	Quality (1-100)
`fit`	string	contain, cover, fill, inside, outside
`dpr`	number	Device Pixel Ratio (1.0-4.0)

View all transform parameters →

Limitations#

File Size: Maximum 50MB
Timeout: 60 seconds (including external server response)
External Server Dependency: May fail depending on external URL server availability
Content-Type Accuracy: External server's Content-Type should be accurate for optimal processing

Next Steps#

Image Transform API - Full transform parameters reference
Size & Layout - Detailed resize guide
Best Practices - Optimization strategies