/performance API

The /performance API returns Lighthouse metrics (accessibility, best practices, performance, PWA information, SEO) for a URL. It also includes useful metrics like latency, time-to-interaction, design contrast other recommendations.

You can check the full Open API schema here.

Quick Start

{
  "url": "https://example.com/"
}

curl -X POST \
  "https://production-sfo.browserless.io/performance?token=YOUR_API_TOKEN_HERE" \
  -H 'Cache-Control: no-cache' \
  -H 'Content-Type': 'application/json' \
  -d '{
  "url": "https://example.com/"
}'

const TOKEN = "YOUR_API_TOKEN_HERE";
const url = `https://production-sfo.browserless.io/performance?token=${TOKEN}`;
const headers = {
  "Cache-Control": "no-cache",
  "Content-Type": "application/json"
};

const data = {
  url: "https://example.com/"
};

const fetchPerformanceMetrics = async () => {
  const response = await fetch(url, {
    method: 'POST',
    headers: headers,
    body: JSON.stringify(data)
  });

  const result = await response.json();
  console.log(result);
};

fetchPerformanceMetrics();

import requests

TOKEN = "YOUR_API_TOKEN_HERE"
url = f"https://production-sfo.browserless.io/performance?token={TOKEN}"
headers = {
    "Cache-Control": "no-cache",
    "Content-Type": "application/json"
}

data = {
    "url": "https://example.com/"
}

response = requests.post(url, headers=headers, json=data)
result = response.json()

print(result)

import java.io.*;
import java.net.URI;
import java.net.http.*;

public class FetchPerformanceMetrics {
    public static void main(String[] args) {
        String TOKEN = "YOUR_API_TOKEN_HERE";
        String url = "https://production-sfo.browserless.io/performance?token=" + TOKEN;

        String jsonData = """
        {
            "url": "https://example.com/"
        }
        """;

        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(url))
            .header("Cache-Control", "no-cache")
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(jsonData))
            .build();

        try {
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
            System.out.println("Response: " + response.body());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

using System;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program {
    static async Task Main(string[] args) {
        string TOKEN = "YOUR_API_TOKEN_HERE";
        string url = $"https://production-sfo.browserless.io/performance?token={TOKEN}";

        string jsonData = @"
        {
            ""url"": ""https://example.com/""
        }";

        using var client = new HttpClient();
        var content = new StringContent(jsonData, Encoding.UTF8, "application/json");

        try {
            var response = await client.PostAsync(url, content);
            response.EnsureSuccessStatusCode();

            var result = await response.Content.ReadAsStringAsync();
            Console.WriteLine("Response: " + result);
        } catch (Exception ex) {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

Response

  // ...
  "audits": {
    "is-on-https": {
      "title": "Uses HTTPS",
      "score": 1
      // ...
    },
    "viewport": {
      "title": "Has a `<meta name=\"viewport\">` tag with `width` or `initial-scale`",
      "score": 1
      // ...
    },
    "first-contentful-paint": {
      "score": 1,
      "displayValue": "0.8 s"
      // ...
    }
    // ...
  }

Each test has a score that indicates how well it performed, where 1 is the maximum and 0 is the lowest.

Additional Examples and Configuration

warning

Due to the number of checks gathered it can take anywhere from several seconds to minutes depending on the site and size of the worker.

By default, the /performance API will gather all the metrics. This will result in a really big JSON response (350kb to 800kb on average) and it will take some seconds (to minutes) to complete.

Gathering Metrics for a Category

You can get metrics from specific categories, using the config property. Just like Lighthouse, available categories are accessibility, best practices, performance, pwa, and seo

{
  "url": "https://example.com",
  "config": {
    "extends": "lighthouse:default",
    "settings": {
      "onlyCategories": ["accessibility"]
    }
  }
}

curl --request POST \
  --url 'https://production-sfo.browserless.io/performance?token=YOUR_API_TOKEN_HERE' \
  --header 'Cache-Control: no-cache' \
  --header 'Content-Type: application/json' \
  --data '{
  "url": "https://browserless.io",
  "config": {
    "extends": "lighthouse:default",
    "settings": {
      "onlyCategories": ["accessibility"]
    }
  }
}'

const TOKEN = "YOUR_API_TOKEN_HERE";
const url = `https://production-sfo.browserless.io/performance?token=${TOKEN}`;
const headers = {
  "Cache-Control": "no-cache",
  "Content-Type": "application/json"
};

const data = {
  url: "https://browserless.io",
  config: {
    extends: "lighthouse:default",
    settings: {
      onlyCategories: ["accessibility"]
    }
  }
};

const fetchPerformanceMetrics = async () => {
  const response = await fetch(url, {
    method: 'POST',
    headers: headers,
    body: JSON.stringify(data)
  });

  const result = await response.json();
  console.log(result);
};

fetchPerformanceMetrics();

import requests

TOKEN = "YOUR_API_TOKEN_HERE"
url = f"https://production-sfo.browserless.io/performance?token={TOKEN}"
headers = {
    "Cache-Control": "no-cache",
    "Content-Type": "application/json"
}

data = {
    "url": "https://browserless.io",
    "config": {
        "extends": "lighthouse:default",
        "settings": {
            "onlyCategories": ["accessibility"]
        }
    }
}

response = requests.post(url, headers=headers, json=data)
result = response.json()

print(result)

import java.io.*;
import java.net.URI;
import java.net.http.*;

public class FetchPerformanceWithConfig {
    public static void main(String[] args) {
        String TOKEN = "YOUR_API_TOKEN_HERE";
        String url = "https://production-sfo.browserless.io/performance?token=" + TOKEN;

        String jsonData = """
        {
            "url": "https://browserless.io",
            "config": {
                "extends": "lighthouse:default",
                "settings": {
                    "onlyCategories": ["accessibility"]
                }
            }
        }
        """;

        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(url))
            .header("Cache-Control", "no-cache")
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(jsonData))
            .build();

        try {
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
            System.out.println("Response: " + response.body());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

using System;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program {
    static async Task Main(string[] args) {
        string TOKEN = "YOUR_API_TOKEN_HERE";
        string url = $"https://production-sfo.browserless.io/performance?token={TOKEN}";

        string jsonData = @"
        {
            ""url"": ""https://browserless.io"",
            ""config"": {
                ""extends"": ""lighthouse:default"",
                ""settings"": {
                    ""onlyCategories"": [""accessibility""]
                }
            }
        }";

        using var client = new HttpClient();
        var content = new StringContent(jsonData, Encoding.UTF8, "application/json");

        try {
            var response = await client.PostAsync(url, content);
            response.EnsureSuccessStatusCode();

            var result = await response.Content.ReadAsStringAsync();
            Console.WriteLine("Response: " + result);
        } catch (Exception ex) {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

This will gather the predefined metrics defined by Lighthouse for that category:

  // ...
  "audits": {
    "aria-command-name": {
      "title": "`button`, `link`, and `menuitem` elements have accessible names",
      "score": 1
      // ...
    },
    "aria-hidden-body": {
      "title": "`[aria-hidden=\"true\"]` is not present on the document `<body>`",
      "score": 1
      // ...
    },
    "aria-hidden-focus": {
      "title": "`[aria-hidden=\"true\"]` elements do not contain focusable descendents",
      "score": 1
      // ...
    },
    // ...
  }

Gathering metrics from a single audit

You can get any specific metrics valid in Lighthouse

{
  "url": "https://browserless.io",
  "config": {
    "extends": "lighthouse:default",
    "settings": {
      "onlyAudits": ["unminified-css"]
    }
  }
}

curl --request POST \
  --url 'https://production-sfo.browserless.io/performance?token=YOUR_API_TOKEN_HERE' \
  --header 'Cache-Control: no-cache' \
  --header 'Content-Type: application/json' \
  --data '{
  "url": "https://browserless.io",
  "config": {
    "extends": "lighthouse:default",
    "settings": {
      "onlyCategories": ["accessibility"]
    }
  }
}'

const TOKEN = "YOUR_API_TOKEN_HERE";
const url = `https://production-sfo.browserless.io/performance?token=${TOKEN}`;
const headers = {
  "Cache-Control": "no-cache",
  "Content-Type": "application/json"
};

const data = {
  url: "https://browserless.io",
  config: {
    extends: "lighthouse:default",
    settings: {
      onlyCategories: ["accessibility"]
    }
  }
};

const fetchPerformanceMetrics = async () => {
  const response = await fetch(url, {
    method: 'POST',
    headers: headers,
    body: JSON.stringify(data)
  });

  const result = await response.json();
  console.log(result);
};

fetchPerformanceMetrics();

import requests

TOKEN = "YOUR_API_TOKEN_HERE"
url = f"https://production-sfo.browserless.io/performance?token={TOKEN}"
headers = {
    "Cache-Control": "no-cache",
    "Content-Type": "application/json"
}

data = {
    "url": "https://browserless.io",
    "config": {
        "extends": "lighthouse:default",
        "settings": {
            "onlyCategories": ["accessibility"]
        }
    }
}

response = requests.post(url, headers=headers, json=data)
result = response.json()

print(result)

import java.io.*;
import java.net.URI;
import java.net.http.*;

public class FetchPerformanceWithConfig {
    public static void main(String[] args) {
        String TOKEN = "YOUR_API_TOKEN_HERE";
        String url = "https://production-sfo.browserless.io/performance?token=" + TOKEN;

        String jsonData = """
        {
            "url": "https://browserless.io",
            "config": {
                "extends": "lighthouse:default",
                "settings": {
                    "onlyCategories": ["accessibility"]
                }
            }
        }
        """;

        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create(url))
            .header("Cache-Control", "no-cache")
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(jsonData))
            .build();

        try {
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
            System.out.println("Response: " + response.body());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

using System;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program {
    static async Task Main(string[] args) {
        string TOKEN = "YOUR_API_TOKEN_HERE";
        string url = $"https://production-sfo.browserless.io/performance?token={TOKEN}";

        string jsonData = @"
        {
            ""url"": ""https://browserless.io"",
            ""config"": {
                ""extends"": ""lighthouse:default"",
                ""settings"": {
                    ""onlyCategories"": [""accessibility""]
                }
            }
        }";

        using var client = new HttpClient();
        var content = new StringContent(jsonData, Encoding.UTF8, "application/json");

        try {
            var response = await client.PostAsync(url, content);
            response.EnsureSuccessStatusCode();

            var result = await response.Content.ReadAsStringAsync();
            Console.WriteLine("Response: " + result);
        } catch (Exception ex) {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

Response example

  // ...
  "audits": {
    "unminified-css": {
      "title": "Minify CSS",
      "score": 1
      // ...
    },
    // ...
  }

Quick Start​

Additional Examples and Configuration​

Gathering Metrics for a Category​

Gathering metrics from a single audit​

Quick Start

Additional Examples and Configuration

Gathering Metrics for a Category

Gathering metrics from a single audit