Screenshot Diff

Compare two screenshots pixel-by-pixel. Provide two URLs or two base64 images, and get back the diff percentage, pixel count, and a visual diff image.

POST/v1/diff

Screenshot Diff requires a Growth+ plan.

Parameters

Parameter	Type	Default	Description
`url_a`	string	—	First URL to screenshot and compare. Use with url_b.
`url_b`	string	—	Second URL to screenshot and compare. Use with url_a.
`image_a`	string	—	First image as base64 string. Use with image_b.
`image_b`	string	—	Second image as base64 string. Use with image_a.
`threshold`	number	0.1	Color distance threshold (0–1). Lower = stricter comparison.
`width`	number	1280	Viewport width when capturing from URLs.
`height`	number	720	Viewport height when capturing from URLs.

You must provide either url_a + url_b or image_a + image_b. Mixing URL and base64 is not supported.

Response

{
  "diff_percent": 12.45,
  "diff_pixels": 114892,
  "total_pixels": 921600,
  "width": 1280,
  "height": 720,
  "threshold": 0.1,
  "diff_image_base64": "iVBORw0KGgo..."
}

Field	Description
`diff_percent`	Percentage of pixels that differ
`diff_pixels`	Absolute count of differing pixels
`total_pixels`	Total pixels compared (width × height)
`diff_image_base64`	Visual diff image — changed pixels highlighted in red

Examples

Compare two URLs:

curl -X POST https://api.snapsharp.dev/v1/diff \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "url_a": "https://example.com",
    "url_b": "https://staging.example.com",
    "width": 1440,
    "threshold": 0.05
  }'

Compare two base64 images:

curl -X POST https://api.snapsharp.dev/v1/diff \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "image_a": "iVBORw0KGgo...",
    "image_b": "iVBORw0KGgo...",
    "threshold": 0.1
  }'

Use cases

Visual regression testing — compare production vs staging before deploy
A/B testing — quantify visual differences between variants
Brand monitoring — detect unauthorized changes to your web pages
QA automation — verify UI changes in CI/CD pipelines

Errors

Code	Error	Description
400	`validation_error`	Must provide either url_a+url_b or image_a+image_b
401	`unauthorized`	Missing or invalid API key
403	`plan_required`	Growth+ plan required
429	`rate_limited`	Rate limit exceeded
500	—	Internal server error