What is baseURL in playwright.config and why use it?

baseURL is a setting under use in playwright.config.js that gives every page in the test a starting address, so page.goto('/catalog.html') becomes a full URL. You use it so tests name only the path, and the same suite can run against a different environment by changing one line.

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Without baseURL, every page.goto() carries the full address of the site. When the team moves from a staging server to production, every test file has to change. With baseURL set once in the config, tests carry only the path, and switching environments is one edit or one environment variable.

baseURL is a context option, so it belongs inside the use block. Placed at the top level of defineConfig, it is not applied, and every relative goto fails.

Playwright builds the full address with the URL() constructor. That applies to page.goto(), page.route(), page.waitForURL(), page.waitForRequest() and page.waitForResponse(). A leading slash matters: with a base of http://localhost:3000/foo/, ./bar.html keeps the /foo/ part, while /bar.html replaces it.

In the example, the config sets baseURL to the practice app. The test calls page.goto('/catalog.html?mock=static&seed=42&autologin=1'). toHaveURL() then proves Playwright resolved it against the base, and the heading check proves the right page loaded.

playwright.config.js(https://practice.learnplayforge.com)

import { defineConfig, devices } from '@playwright/test';

export default defineConfig({
  testDir: '.',
  reporter: 'list',
  use: {
    baseURL: 'https://practice.learnplayforge.com',
  },
  projects: [{ name: 'chromium', use: { ...devices['Desktop Chrome'] } }],
});

// base-url.spec.js
import { test, expect } from '@playwright/test';

test('a relative path is resolved against baseURL', async ({ page }) => {
  await page.goto('/catalog.html?mock=static&seed=42&autologin=1');
  await expect(page).toHaveURL('https://practice.learnplayforge.com/catalog.html?mock=static&seed=42&autologin=1');
  await expect(page.locator('#grid-heading')).toHaveText('All products');
});

Output

1 passed (1.6s)

Test yourself

Your config has use: { baseURL: 'https://practice.learnplayforge.com' }. A test calls page.goto('/login.html'). Which address does the browser open?

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What is baseURL in playwright.config and why use it?

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