Get Started with the PageSpeed Insights API

Use the PageSpeed Insights API to:

Measure the performance of a web page.
Get suggestions on how to improve the page's performance, accessibility, and SEO.

The PageSpeed Insights API returns real-world data from the Chrome User Experience Report and lab data from Lighthouse.

API Explorer

To make calls to the PageSpeed Insights API without writing any code, check out the API Explorer.

Acquiring and using an API key

Or create one in the Credentials page.

After you have an API key, your application can append the query parameter key=yourAPIKey to all request URLs.

The API key is safe for embedding in URLs; it doesn't need any encoding.

`curl`

To try out the PageSpeed Insights API from the command line:

Open a terminal.

Run the following command. Replace yourAPIKey with your API key.

curl https://www.googleapis.com/pagespeedonline/v5/runPagespeed?url=https://web.dev/&key=yourAPIKey

The response is a JSON object. See Response to learn more about each of the properties in the response object.

{
 "captchaResult": "CAPTCHA_NOT_NEEDED",
 "kind": "pagespeedonline#result",
 "id": "https://developers.google.com/",
 "loadingExperience": {
  "id": "https://developers.google.com/",
  "metrics": {
   "FIRST_CONTENTFUL_PAINT_MS": {
    "percentile": 3482,
    "distributions": [
     {
      "min": 0,
      "max": 1000,
      "proportion": 0.37151728768042963
     },
     {
      "min": 1000,
      "max": 2500,
      "proportion": 0.4244153519077991
     },
     {
      "min": 2500,
      "proportion": 0.2040673604117713
     }
    ],
    "category": "SLOW"
   },
   "FIRST_INPUT_DELAY_MS": {
    "percentile": 36,
    "distributions": [
     {
      "min": 0,
      "max": 50,
      "proportion": 0.960628961482204
     },
     {
      "min": 50,
      "max": 250,
      "proportion": 0.02888834714773281
     },
     {
      "min": 250,
      "proportion": 0.010482691370063388
     }
    ],
    "category": "FAST"
   }
  },
  "overall_category": "SLOW",
  "initial_url": "https://developers.google.com/"
 },
 "originLoadingExperience": {
  "id": "https://developers.google.com",
  "metrics": {
   "FIRST_CONTENTFUL_PAINT_MS": {
    "percentile": 2761,
    "distributions": [
     {
      "min": 0,
      "max": 1000,
      "proportion": 0.4236433226493666
     },
     {
      "min": 1000,
      "max": 2500,
      "proportion": 0.45045120795679117
     },
     {
      "min": 2500,
      "proportion": 0.1259054693938423
     }
    ],
    "category": "SLOW"
   },
   "FIRST_INPUT_DELAY_MS": {
    "percentile": 45,
    "distributions": [
     {
      "min": 0,
      "max": 50,
      "proportion": 0.9537371485251699
     },
     {
      "min": 50,
      "max": 250,
      "proportion": 0.03044972719889055
     },
     {
      "min": 250,
      "proportion": 0.01581312427593959
     }
    ],
    "category": "FAST"
   }
  },
  "overall_category": "SLOW",
  "initial_url": "https://developers.google.com/"
 },
 "lighthouseResult": {
  "requestedUrl": "https://developers.google.com/",
  "finalUrl": "https://developers.google.com/",
  "lighthouseVersion": "3.2.0",
  "userAgent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/72.0.3584.0 Safari/537.36",
  "fetchTime": "2018-11-01T03:03:58.394Z",
  "environment": {
   "networkUserAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3559.0 Safari/537.36",
   "hostUserAgent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/72.0.3584.0 Safari/537.36",
   "benchmarkIndex": 590.0
  },
  "runWarnings": [],
  "configSettings": {
   "emulatedFormFactor": "desktop",
   "locale": "en-US",
   "onlyCategories": [
    "performance"
   ]
  },
  "audits": {
   "estimated-input-latency": {
    "id": "estimated-input-latency",
    "title": "Estimated Input Latency",
    "description": "The score above is an estimate of how long your app takes to respond to user input, in milliseconds, during the busiest 5s window of page load. If your latency is higher than 50 ms, users may perceive your app as laggy. [Learn more](https://developers.google.com/web/tools/lighthouse/audits/estimated-input-latency).",
    "score": 1.0,
    "scoreDisplayMode": "numeric",
    "displayValue": "30 ms"
   },
   "uses-rel-preconnect": {
    "id": "uses-rel-preconnect",
    "title": "Preconnect to required origins",
    "description": "Consider adding preconnect or dns-prefetch resource hints to establish early connections to important third-party origins. [Learn more](https://developers.google.com/web/fundamentals/performance/resource-prioritization#preconnect).",
    "score": 1.0,
    "scoreDisplayMode": "numeric",
    "details": {
     "headings": [],
     "type": "opportunity",
     "items": [],
     "overallSavingsMs": 0.0
    }
   },
   ...
  },
  "categories": {
   "performance": {
    "id": "performance",
    "title": "Performance",
    "score": 0.96,
    "auditRefs": [
     {
      "id": "first-contentful-paint",
      "weight": 3.0,
      "group": "metrics"
     },
     {
      "id": "first-meaningful-paint",
      "weight": 1.0,
      "group": "metrics"
     },
     ...
    ]
   }
  },
  "categoryGroups": {
   "a11y-element-names": {
    "title": "Elements Have Discernible Names",
    "description": "These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader."
   },
   "a11y-language": {
    "title": "Page Specifies Valid Language",
    "description": "These are opportunities to improve the interpretation of your content by users in different locales."
   },
   ...
  },
  "i18n": {
   "rendererFormattedStrings": {
    "varianceDisclaimer": "Values are estimated and may vary.",
    "opportunityResourceColumnLabel": "Opportunity",
    "opportunitySavingsColumnLabel": "Estimated Savings",
    "errorMissingAuditInfo": "Report error: no audit information",
    "errorLabel": "Error!",
    "warningHeader": "Warnings: ",
    "auditGroupExpandTooltip": "Show audits",
    "passedAuditsGroupTitle": "Passed audits",
    "notApplicableAuditsGroupTitle": "Not applicable",
    "manualAuditsGroupTitle": "Additional items to manually check",
    "toplevelWarningsMessage": "There were issues affecting this run of Lighthouse:",
    "scorescaleLabel": "Score scale:",
    "crcLongestDurationLabel": "Maximum critical path latency:",
    "crcInitialNavigation": "Initial Navigation",
    "lsPerformanceCategoryDescription": "[Lighthouse](https://developers.google.com/web/tools/lighthouse/) analysis of the current page on an emulated mobile network. Values are estimated and may vary.",
    "labDataTitle": "Lab Data"
   }
  }
 },
 "analysisUTCTimestamp": "2018-11-01T03:03:58.394Z"
}

JavaScript

To try out the PageSpeed Insights API from JavaScript:

Copy the code below. The code uses the PageSpeed Insights API to measure the performance of https://web.dev/, and then it displays the results.

/**
 * Fetches and displays PageSpeed Insights data.
 */
async function run() {
  const apiEndpoint =
      'https://www.googleapis.com/pagespeedonline/v5/runPagespeed';
  const targetUrl = 'https://web.dev/';

  const url = new URL(apiEndpoint);
  url.searchParams.set('url', targetUrl);

  try {
    const response = await fetch(url);
    if (!response.ok) {
      throw new Error(`HTTP error! status: ${response.status}`);
    }
    const json = await response.json();

    // See
    // https://developers.google.com/speed/docs/insights/v5/reference/pagespeedapi/runpagespeed#response
    // to learn more about each of the properties in the response object.

    showInitialContent(json.id);

    const cruxMetrics = {
      'First Contentful Paint':
          json.loadingExperience.metrics.FIRST_CONTENTFUL_PAINT_MS?.category,
      'Interaction to Next Paint':
          json.loadingExperience.metrics.INTERACTION_TO_NEXT_PAINT?.category,
    };
    showCruxContent(cruxMetrics);

    const lighthouse = json.lighthouseResult;
    const lighthouseMetrics = {
      'First Contentful Paint':
          lighthouse.audits['first-contentful-paint']?.displayValue,
      'Speed Index': lighthouse.audits['speed-index']?.displayValue,
      'Largest Contentful Paint':
          lighthouse.audits['largest-contentful-paint']?.displayValue,
      'Total Blocking Time':
          lighthouse.audits['total-blocking-time']?.displayValue,
      'Time To Interactive': lighthouse.audits['interactive']?.displayValue,
    };
    showLighthouseContent(lighthouseMetrics);
  } catch (error) {
    console.error('Fetching PageSpeed Insights failed:', error);
    document.body.textContent =
        `Failed to fetch PageSpeed data. Check the console for errors.`;
  }
}

/**
 * Displays initial content, including the page ID.
 * @param {string} id The ID of the page being tested.
 */
function showInitialContent(id) {
  document.body.innerHTML = '';  // Clear previous content
  const title = document.createElement('h1');
  title.textContent = 'PageSpeed Insights API Demo';
  document.body.appendChild(title);

  const page = document.createElement('p');
  page.textContent = `Page tested: ${id}`;
  document.body.appendChild(page);
}

/**
 * Displays CrUX metrics.
 * @param {!Object} cruxMetrics The CrUX metrics to display.
 */
function showCruxContent(cruxMetrics) {
  const cruxHeader = document.createElement('h2');
  cruxHeader.textContent = 'Chrome User Experience Report Results';
  document.body.appendChild(cruxHeader);

  for (const key in cruxMetrics) {
    const p = document.createElement('p');
    p.textContent = `${key}: ${cruxMetrics[key]}`;
    document.body.appendChild(p);
  }
}

/**
 * Displays Lighthouse metrics.
 * @param {!Object} lighthouseMetrics The Lighthouse metrics to display.
 */
function showLighthouseContent(lighthouseMetrics) {
  const lighthouseHeader = document.createElement('h2');
  lighthouseHeader.textContent = 'Lighthouse Results';
  document.body.appendChild(lighthouseHeader);

  for (const key in lighthouseMetrics) {
    const p = document.createElement('p');
    p.textContent = `${key}: ${lighthouseMetrics[key]}`;
    document.body.appendChild(p);
  }
}

run();

Paste the code into a script tag in an HTML file.
Open the HTML file in a browser. Upon successful completion, your page will look like Figure 1.

Figure 1. The JavaScript demo

Next steps

See Response to learn more about each of the properties in the response object.
See About the PageSpeed Insights API to learn more about how performance measurements are calculated.

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