WebPerf Snippets runs on your own machine — the client starts it, so there is no endpoint to ping. 630 installs a week from npm. Last commit 24 Oct 2026.
Measure Core Web Vitals and debug web performance with 56 snippets in a headless Chromium
We read the source, 37 min ago · rules 995398eba69f
What this server is able to do. For an MCP server this is often the job itself — a terminal server runs commands because that is what it is for. Listed so you know what you are plugging in, not as an accusation.
этот файл ставится пользователю, но в репозитории его нет
chrome.devtools.inspectedWindow.eval(expression, (result, exception) => {
| **⚫ Unknown** | Inline scripts, eval(), no source attribution | **Need investigation** - Likely your code |
Is this your server and something here is wrong? Tell us — corrections are free and do not require a plan.
We found places where it runs commands, builds paths or queries from values it is given. None of that is a flaw by itself — it becomes one when the code changes, and code changes quietly between releases. We re-read it on every one.
This server runs on your own machine — install it with the package manager and the client starts it for you. Package name taken from the official registry entry.
claude mcp add webperf-snippets -- npx -y webperf-snippets
{
"mcpServers": {
"webperf-snippets": {
"command": "npx",
"args": [
"-y",
"webperf-snippets"
]
}
}
}
[mcp_servers.webperf-snippets]
command = "npx"
args = ["-y", "webperf-snippets"]
{
"mcpServers": {
"webperf-snippets": {
"command": "npx",
"args": [
"-y",
"webperf-snippets"
]
}
}
}
{
"servers": {
"webperf-snippets": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"webperf-snippets"
]
}
}
}
Optional settings from the registry entry, left out of the block above:
CRUX_API_KEY (Chrome UX Report API key for the field data of get_crux; the other tools work without it).
Design systems, layout and motion guidance for AI agents, plus headless Chromium visual QA.
Core Web Vitals (LCP, INP, CLS) per URL from the Chrome UX Report, with daily checks on Pro.
Create and preview self-contained web apps in iPhone, Duo, iPad, and Headless views.
Renders web pages into structured, agent-readable representations using headless Chromium.
Real-user Core Web Vitals for any website with enough traffic, from Google's Chrome UX Report…
Find and compare headless apps (CLI, MCP, API) for agents, with sources, lessons and changes.
Render Markdown and LLM output into accessible PDF/UA-1 PDFs. No headless Chromium.
Browserless MCP — wraps the Browserless headless-Chromium REST API (browserless.io)
Answers built from our own checks of this server.