Website Carbon Estimate

Estimate the CO2 per page view of a website using the Website Carbon method, with an A to F rating and a yearly figure.

Pay by wallet (x402) website-carbon-estimate

Example

Input

{
  "url": "https://strale.dev"
}

Answer

{
  "url": "https://strale.dev",
  "rating": "A",
  "methodology": "Website Carbon / Sustainable Web Design model",
  "page_size_kb": 3,
  "annual_co2_kg": 0.1,
  "green_hosting": "unknown",
  "page_size_bytes": 3239,
  "recommendations": [
    "This page is already lightweight. Maintain current optimization practices."
  ],
  "transfer_encoding": "gzip",
  "co2_grams_per_view": 0.0008,
  "annual_co2_kg_custom": null,
  "cleaner_than_percent": 100
}

Inputs

Field	Type	Required	What it is
`url`	string	Yes	—

Output fields

How reliably each field appears in a successful answer.

Field	Type	Appears
`rating`	string	Always (present in every successful answer)
`page_size_kb`	number	Always (present in every successful answer)
`annual_co2_kg`	number	Always (present in every successful answer)
`co2_grams_per_view`	number	Always (present in every successful answer)

How to call it

The same tool through each route. MCP clients reach it through Strale’s server at https://api.strale.io/mcp; the call below is what the agent sends.

# Needs an API key. max_price_cents caps what this call may cost.
curl -X POST https://api.strale.io/v1/do \
  -H "Authorization: Bearer $STRALE_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "capability_slug": "website-carbon-estimate",
    "inputs": {
      "url": "https://strale.dev"
    },
    "max_price_cents": 5
  }'

{
  "tool": "strale_execute",
  "arguments": {
    "slug": "website-carbon-estimate",
    "inputs": {
      "url": "https://strale.dev"
    },
    "max_price_cents": 5
  }
}

import { Strale } from "straleio";

const strale = new Strale({ apiKey: process.env.STRALE_API_KEY! });
const result = await strale.do({
  capability_slug: "website-carbon-estimate",
  inputs: {
    "url": "https://strale.dev"
  },
  max_price_cents: 5,
});

import os
from straleio import Strale, DoRequest

strale = Strale(api_key=os.environ["STRALE_API_KEY"])
result = strale.do(DoRequest(
    capability_slug="website-carbon-estimate",
    inputs={
        "url": "https://strale.dev",
    },
    max_price_cents=5,
))

# No account. The first request answers 402 with the price in USDC;
# an x402 client pays it from your wallet and repeats the request.
curl -i 'https://api.strale.io/x402/v2/website-carbon-estimate?url=https%3A%2F%2Fstrale.dev'

Limitations

Emissions depend on more than page weight
Carbon estimates based on page weight and transfer size — actual emissions depend on server location, CDN, and energy grid mix
What to do instead: Compare estimates between pages; obtain a separate assessment for formal carbon reporting.
Pages transferring more than 100 MiB are not measured
Pages transferring more than 100 MiB are refused with a caller_input error rather than measured. The call is not charged.