visualdiff

visualdiff

visualdiff wraps the SnapDiff visual-testing API: verify that a UI change matches what you meant to do, diff two pages (or a page against a stored baseline), capture a screenshot of any URL, and render raw HTML/CSS straight to an image. One binary serves a command-line interface and a stdio MCP server.

An API key is required. Set SNAPDIFF_API_KEY to a key from the SnapDiff dashboard; calls fail before any request is made when it is missing. The API base URL can be overridden with SNAPDIFF_API_URL; when it is not set, calls go to https://api.snapdiff.ai/v1.

Install

npx @reneturcios/visualdiff screenshot https://example.com

Or run the container image:

docker run -i -e SNAPDIFF_API_KEY=sk_live_... ghcr.io/cloudcorprecords/visualdiff

The container defaults to the MCP server (see below). Pass CLI arguments to use it as a CLI instead.

CLI

export SNAPDIFF_API_KEY=sk_live_...

visualdiff verify myproj pricing https://staging.example.com/pricing "added a yearly billing toggle"
visualdiff compare https://staging.example.com --before https://www.example.com
visualdiff compare http://localhost:3000 --project myproj --page-name homepage
visualdiff screenshot https://example.com --width 800 --full-page
visualdiff html-to-image "<h1>Hello</h1>" --css "h1 { color: navy; }" --width 1200 --height 630

visualdiff --version

Commands print the upstream JSON payload. Exit codes: 0 on success, 1 when a call fails (including a missing API key or an upstream API error), 2 for usage errors.

MCP server

One bin serves both faces. The mcp subcommand starts a stdio MCP server:

npx -y @reneturcios/visualdiff mcp

MCP client configuration:

{
  "mcpServers": {
    "visualdiff": {
      "command": "npx",
      "args": ["-y", "@reneturcios/visualdiff", "mcp"],
      "env": { "SNAPDIFF_API_KEY": "sk_live_..." }
    }
  }
}

Tools

Tool	Input	What it returns
snapdiff_verify_ui_change	project, page_name, after, intent (all required); optional intent_regions, branch, threshold, match_tolerance_percent, ignore_selectors, full_page	A verdict (pass, expected_change_detected, unexpected_regression, no_change_detected, or needs_human_review), a next_action, and a review_url. Requires a project with a stored page baseline.
snapdiff_compare_pages	after (required); plus before, or project + page_name for baseline mode; optional branch, threshold, ignore_selectors, full_page	A diff percentage plus a highlighted diff image.
snapdiff_capture_screenshot	url (required); optional full_page, dark_mode, selector, width	A screenshot of the page.
snapdiff_html_to_image	html (required); optional css, width, height	The rendered image (OG cards, social images, email headers).

Each tool is sent as a POST to a per-tool endpoint under the base URL with the API key as a Bearer token. Optional arguments that are not supplied are omitted from the request body entirely.

Development

npm install
npm run build   # tsc -> dist/
npm test        # node test runner over test/*.test.ts, no network (fake fetch fixtures)
npm run dev     # run the CLI from source via tsx

License

MIT — see LICENSE.