Playwright Has a Free API You Should Know About

Playwright is more than an E2E testing tool — it has a powerful API for browser automation, web scraping, PDF generation, and building custom testing infrastructure.

Browser Automation API

Playwright's core API gives you full browser control:

import { chromium } from "playwright"

const browser = await chromium.launch({ headless: true })
const context = await browser.newContext({
  viewport: { width: 1920, height: 1080 },
  userAgent: "Custom Agent",
  locale: "en-US",
  geolocation: { latitude: 40.7128, longitude: -74.0060 },
  permissions: ["geolocation"]
})

const page = await context.newPage()
await page.goto("https://example.com")

// Smart waiting — no sleep() needed
await page.getByRole("button", { name: "Submit" }).click()
await page.waitForURL("**/success")

await browser.close()

Network Interception

Intercept and modify network requests:

// Mock API responses
await page.route("**/api/users", async (route) => {
  await route.fulfill({
    status: 200,
    contentType: "application/json",
    body: JSON.stringify([{ id: 1, name: "Test User" }])
  })
})

// Block resources for faster scraping
await page.route("**/*.{png,jpg,gif,css,woff2}", route => route.abort())

// Modify requests
await page.route("**/api/**", async (route) => {
  const headers = {
    ...route.request().headers(),
    "Authorization": "Bearer custom-token"
  }
  await route.continue({ headers })
})

// Capture responses
page.on("response", async (response) => {
  if (response.url().includes("/api/data")) {
    const json = await response.json()
    console.log("Captured:", json)
  }
})

PDF Generation

Generate PDFs from any webpage:

const page = await browser.newPage()
await page.goto("https://example.com/report")

await page.pdf({
  path: "report.pdf",
  format: "A4",
  margin: { top: "1cm", bottom: "1cm", left: "1cm", right: "1cm" },
  printBackground: true,
  displayHeaderFooter: true,
  headerTemplate: "<span style=\"font-size:10px\">Report</span>",
  footerTemplate: "<span style=\"font-size:10px\">Page <span class=\"pageNumber\"></span> of <span class=\"totalPages\"></span></span>"
})

Parallel Execution

Run browsers in parallel for speed:

import { chromium } from "playwright"

const urls = ["url1", "url2", "url3", "url4", "url5"]

const browser = await chromium.launch()
const results = await Promise.all(
  urls.map(async (url) => {
    const context = await browser.newContext()
    const page = await context.newPage()
    try {
      await page.goto(url, { timeout: 10000 })
      const title = await page.title()
      const text = await page.locator("main").textContent()
      return { url, title, text }
    } catch (e) {
      return { url, error: e.message }
    } finally {
      await context.close()
    }
  })
)
await browser.close()

Test API — Built-in Assertions

Playwright Test has powerful web-first assertions:

import { test, expect } from "@playwright/test"

test("user flow", async ({ page }) => {
  await page.goto("/login")

  await page.getByLabel("Email").fill("[e-mail]")
  await page.getByLabel("Password").fill("pass123")
  await page.getByRole("button", { name: "Sign in" }).click()

  // Auto-retrying assertions
  await expect(page).toHaveURL("/dashboard")
  await expect(page.getByText("Welcome")).toBeVisible()
  await expect(page.getByRole("table")).toContainText("Recent")
})

Codegen — Record Tests

npx playwright codegen https://example.com

Opens a browser and records your actions as test code.

Key Takeaways

• Browser API for full automation with smart waiting
• Network interception to mock, block, or modify requests
• PDF generation from any webpage
• Parallel contexts for high-throughput scraping
• Test assertions that auto-retry
• Codegen to record tests visually
• Works with Chromium, Firefox, and WebKit

See Playwright docs for the full API.

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