@webmarkjs/cli

Measure a URL's web performance from your terminal. Runs Lighthouse the specified number of times and reports the distribution (avg, σ, min, max, p75, p99) instead of a single noisy number.

Install

Install globally to use webmark anywhere:

npm install -g @webmarkjs/cli

Or run once without installing:

npx @webmarkjs/cli https://example.com

Requirements

• Node.js 24+
• Chrome or Chromium installed. webmark launches whatever Chrome it finds in headless mode.

If no Chrome is found, the command fails with a clear message:

error: Could not launch Chrome to run the measurement.
hint:  Install Chrome or Chromium, or point CHROME_PATH at an existing binary.

To use a specific browser:

CHROME_PATH=/usr/bin/chromium webmark https://example.com

Usage

webmark <url> [options]

The scheme is optional — webmark example.com is treated as https://example.com.

Options

| Option | Default | Description | |--------|---------|-------------| | -n, --runs <count> | 5 | Number of measurement runs | | --json | off | Output JSON instead of a table | | --silent | off | Suppress per-run progress on stderr | | -h, --help | | Show help | | -v, --version | | Show version |

Output

https://example.com/

metric  p50    sd     (min…max)     p75    p99
LCP     1.7s   210ms  (1.5s…2.3s)   1.9s   2.3s
FCP     1.1s   130ms  (900ms…1.3s)  1.2s   1.3s
CLS     0.021  0.012  (0.000…0.040) 0.031  0.040
TTI     2.0s   330ms  (1.7s…2.8s)   2.3s   2.8s

p50 is the median — the midpoint of the distribution. Unlike the arithmetic mean it is not skewed by outliers (a single slow run caused by a CPU spike won't pull it up).

Color is shown only in an interactive terminal and is disabled by NO_COLOR, so piped or redirected output stays plain.

Examples

Run more times for a tighter distribution:

webmark https://example.com --runs 10

Save results as JSON (measurements go to stdout, progress to stderr):

webmark https://example.com --json > result.json

Pipe into jq:

webmark https://example.com --json | jq '.field.lcp.p75'

Suppress progress output entirely:

webmark https://example.com --silent

Check the exit code in a script:

webmark https://example.com --silent || echo "measurement failed"

Exit codes

| Code | Meaning | |------|---------| | 0 | Success | | 1 | Runtime error (e.g. invalid URL, Chrome not found) | | 2 | Usage error (e.g. missing URL) |

JSON output schema

{
  "url": "https://example.com/",
  "field": {
    "lcp": { "p50": 1700, "min": 1500, "max": 2300, "p75": 1900, "p99": 2300, "sd": 210, "values": [...] },
    "fcp": { ... },
    "cls": { ... },
    "ttfb": { ... }
  },
  "lab": {
    "tbt": { ... },
    "tti": { ... },
    "si":  { ... }
  }
}

Time-based metrics are in milliseconds. CLS is a unitless score.

License

MIT