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Overwatch API

Get Core Web Vitals (CrUX field data)

GET
/v1/sites/{id}/crux
curl --request GET \
  --url https://api.overwatch.weareheavy.dev/v1/sites/2489E9AD-2EE2-8E00-8EC9-32D5F69181C0/crux \
  --header 'x-api-key: <x-api-key>'

Real-user Core Web Vitals for the site’s origin, from the Chrome UX Report (CrUX): the latest p75 values for LCP, INP, CLS, and TTFB, a pass/fail Core Web Vitals verdict, movement versus ~7 and ~28 days ago, and the stored weekly series for trend charts.

The verdict follows the standard assessment: pass iff all three core metrics’ p75 are good — LCP ≤ 2.5 s, INP ≤ 200 ms, CLS ≤ 0.1 — and null when any core metric is missing for the period.

Responds 404 until the daily CrUX sync has found data for the origin (low-traffic origins may never be in the CrUX dataset), or when the Performance app is not enabled for the site.

Authorizations

Section titled “ Authorizations ”

Parameters

Section titled “ Parameters ”

Path Parameters

Section titled “ Path Parameters ”
id
required
string format: uuid

The site’s UUID.

Responses

Section titled “ Responses ”

200

Section titled “ 200 ”

The latest metrics, verdict, deltas, and weekly series.

Media typeapplication/json
object
formFactor
required

The CrUX form factor the data covers (ALL — all devices).

string
checkedAt
required

Epoch ms of the last CrUX sync for this site.

integer | null
latest
required

One CrUX window’s p75 metrics; a metric is null when CrUX has no data for it.

object
periodEnd
required

The last day of the collection window (YYYY-MM-DD).

string format: date
lcp
required

Largest Contentful Paint p75, in milliseconds.

number | null
inp
required

Interaction to Next Paint p75, in milliseconds.

number | null
cls
required

Cumulative Layout Shift p75 (unitless).

number | null
ttfb
required

Time to First Byte p75, in milliseconds.

number | null
verdict
required

The Core Web Vitals assessment for the latest window.

string | null
Allowed values: pass fail
deltas
required

Per-metric movement vs the point closest to 7 / 28 days back.

object
d7
required

Per-metric movement vs a baseline; null when either side is missing.

object
lcp
required
number | null
inp
required
number | null
cls
required
number | null
ttfb
required
number | null
d28
required

Per-metric movement vs a baseline; null when either side is missing.

object
lcp
required
number | null
inp
required
number | null
cls
required
number | null
ttfb
required
number | null
series
required

Weekly p75 points, oldest → newest (each a rolling 28-day window).

Array<object>

One CrUX window’s p75 metrics; a metric is null when CrUX has no data for it.

object
periodEnd
required

The last day of the collection window (YYYY-MM-DD).

string format: date
lcp
required

Largest Contentful Paint p75, in milliseconds.

number | null
inp
required

Interaction to Next Paint p75, in milliseconds.

number | null
cls
required

Cumulative Layout Shift p75 (unitless).

number | null
ttfb
required

Time to First Byte p75, in milliseconds.

number | null
Example
{
  "formFactor": "ALL",
  "checkedAt": 1753300000000,
  "latest": {
    "periodEnd": "2026-07-20",
    "lcp": 2100,
    "inp": 140,
    "cls": 0.05,
    "ttfb": 600
  },
  "verdict": "pass",
  "deltas": {
    "d7": {
      "lcp": -80,
      "inp": 5,
      "cls": 0,
      "ttfb": -20
    },
    "d28": {
      "lcp": -240,
      "inp": -15,
      "cls": -0.01,
      "ttfb": -60
    }
  },
  "series": [
    {
      "periodEnd": "2026-07-20",
      "lcp": 2100,
      "inp": 140,
      "cls": 0.05,
      "ttfb": 600
    }
  ]
}

401

Section titled “ 401 ”

Missing or invalid credentials.

Media typeapplication/json
object
error
required

A human-readable error message.

string
Example
{
  "error": "invalid api key"
}

404

Section titled “ 404 ”

The site was not found, the Performance app is not enabled, or the origin has no CrUX data yet.

Media typeapplication/json
object
error
required

A human-readable error message.

string
Example
{
  "error": "no CrUX data for this origin"
}