HTTP Requests

Learn how to make HTTP requests in k6, use different HTTP methods, and organize URLs for better metrics analysis.

HTTP requests are the foundation of most k6 load tests. The k6/http module provides methods for all standard HTTP operations.

Making HTTP requests

The simplest HTTP request is a GET request:

import http from 'k6/http';

export default function () {
  http.get('http://test.k6.io');
}

POST request with payload

Here’s a more complex example showing a POST request with JSON payload:

import http from 'k6/http';

export default function () {
  const url = 'http://test.k6.io/login';
  const payload = JSON.stringify({
    email: 'aaa',
    password: 'bbb',
  });

  const params = {
    headers: {
      'Content-Type': 'application/json',
    },
  };

  http.post(url, payload, params);
}

Available HTTP methods

The k6/http module supports all standard HTTP methods:

Method	Description
http.get()	Issue an HTTP GET request
http.post()	Issue an HTTP POST request
http.put()	Issue an HTTP PUT request
http.patch()	Issue an HTTP PATCH request
http.del()	Issue an HTTP DELETE request
http.head()	Issue an HTTP HEAD request
http.options()	Issue an HTTP OPTIONS request
http.request()	Issue any type of HTTP request
http.batch()	Issue multiple HTTP requests in parallel

Batch requests

Use http.batch() to send multiple requests in parallel, similar to how browsers load resources:

import http from 'k6/http';

export default function () {
  const responses = http.batch([
    ['GET', 'https://test.k6.io/'],
    ['GET', 'https://test.k6.io/contacts.php'],
    ['GET', 'https://test.k6.io/news.php'],
  ]);
  
  // All requests execute in parallel
}

HTTP request parameters

The third parameter to HTTP methods accepts an object with request configuration:

Headers

import http from 'k6/http';

export default function () {
  const params = {
    headers: {
      'Content-Type': 'application/json',
      'Authorization': 'Bearer token123',
    },
  };
  
  http.get('https://test.k6.io', params);
}

Following redirects

By default, k6 automatically follows redirects. You can customize this behavior:

Global setting

Set maxRedirects in options to configure redirect behavior for all requests:

export const options = {
  maxRedirects: 10,
};

Per-request setting

Override the global setting for specific requests:

http.get('https://test.k6.io', { redirects: 0 }); // Don't follow redirects

HTTP request tags

k6 automatically tags HTTP requests with metadata for filtering and analysis:

Tag	Description	Example
name	URL or custom name	http://test.k6.io
method	HTTP method	GET, POST
status	Response status code	200, 404
url	Request URL	http://test.k6.io
group	Group name (if in a group)	::user login
scenario	Scenario name	default
expected_response	Whether response was expected	true, false

Example tagged output

Here’s how k6 stores metrics with tags:

{
  "type": "Point",
  "metric": "http_req_duration",
  "data": {
    "time": "2017-06-02T23:10:29.52444541+02:00",
    "value": 586.831127,
    "tags": {
      "expected_response": "true",
      "group": "",
      "method": "GET",
      "name": "http://test.k6.io",
      "scenario": "default",
      "status": "200",
      "url": "http://test.k6.io"
    }
  }
}

URL grouping

When testing dynamic URLs, you’ll want to group them to prevent metrics fragmentation.

The problem: dynamic URLs

This code creates 100 different metrics, one for each unique URL:

import http from 'k6/http';

export default function () {
  for (let id = 1; id <= 100; id++) {
    http.get(`http://example.com/posts/${id}`);
    // Results in: tags.name="http://example.com/posts/1",
    //             tags.name="http://example.com/posts/2", etc.
  }
}

This makes analysis difficult and consumes more memory.

Solution 1: Custom name tag

Set a custom name tag to group dynamic URLs:

import http from 'k6/http';

export default function () {
  for (let id = 1; id <= 100; id++) {
    http.get(`http://example.com/posts/${id}`, {
      tags: { name: 'PostsItemURL' },
    });
    // All requests now have: tags.name="PostsItemURL"
  }
}

Now all 100 requests are aggregated into a single metric.

Solution 2: http.url template

Use the http.url template literal wrapper:

import http from 'k6/http';

export default function () {
  for (let id = 1; id <= 100; id++) {
    http.get(http.url`http://example.com/posts/${id}`);
    // Results in: tags.name="http://example.com/posts/${{}}"
  }
}

This automatically groups URLs by replacing variable parts with ${}.

Response object

HTTP methods return a Response object with request/response details:

import http from 'k6/http';
import { check } from 'k6';

export default function () {
  const res = http.get('https://test.k6.io');
  
  console.log(res.status);        // 200
  console.log(res.body.length);   // Response body size
  console.log(res.timings.duration); // Request duration in ms
  
  check(res, {
    'is status 200': (r) => r.status === 200,
    'body size > 0': (r) => r.body.length > 0,
  });
}

Useful response properties

res.status

HTTP status code (200, 404, etc.)

res.body

Response body as string

res.json()

Parse response body as JSON

res.timings

Detailed timing breakdown

res.headers

Response headers

res.cookies

Response cookies

Complete example

Here’s a comprehensive example combining multiple concepts:

import http from 'k6/http';
import { check, sleep } from 'k6';

export const options = {
  vus: 10,
  duration: '30s',
};

const baseUrl = 'https://quickpizza.grafana.com';

export default function () {
  // GET request with custom tags
  const listRes = http.get(`${baseUrl}/api/pizzas`, {
    tags: { name: 'ListPizzas' },
  });
  
  check(listRes, {
    'list status is 200': (r) => r.status === 200,
  });
  
  // POST request with JSON payload
  const createPayload = JSON.stringify({
    name: 'Test Pizza',
    toppings: ['cheese', 'pepperoni'],
  });
  
  const createRes = http.post(
    `${baseUrl}/api/pizzas`,
    createPayload,
    {
      headers: { 'Content-Type': 'application/json' },
      tags: { name: 'CreatePizza' },
    }
  );
  
  check(createRes, {
    'create status is 201': (r) => r.status === 201,
  });
  
  // Batch parallel requests
  http.batch([
    ['GET', `${baseUrl}/`, null, { tags: { name: 'Homepage' } }],
    ['GET', `${baseUrl}/api/status`, null, { tags: { name: 'Status' } }],
  ]);
  
  sleep(1);
}

Best practices

Group dynamic URLs

Use name tags or http.url to prevent metric fragmentation with dynamic URLs.

Use meaningful names

Tag requests with descriptive names for easier analysis.

Check responses

Always validate critical responses with checks.

Batch when possible

Use http.batch() to simulate realistic browser behavior.