Reliability
Playwright:
- Cross-browser Testing: Compatible with Chromium, Firefox, and WebKit for consistent behavior.
- Network Interception and Mocking: Built-in support aids web and API testing.
- Auto-waiting: Waits for elements before interaction, reducing flakiness.
Selenium:
- Cross-browser Testing: Supports many browsers, may need extra setup.
- Network Interception and Mocking: Requires third-party tools.
- Flakiness: WebDriver-based tests may be flaky due to browser differences.
Speed
Playwright:
- Parallel Execution: Easy parallel testing improves speed.
- Headless Mode: Optimized for faster performance.
- Modern APIs: Allows fast, clean scripting.
Selenium:
- Parallel Execution: Possible with Grid but setup is complex.
- Execution Speed: Slower due to frequent communication via WebDriver.
- Headless Mode: Less efficient than Playwright.
Summary and Final Thoughts
Playwright (with PyTest) offers modern, fast automation ideal for modern apps. Selenium is stable, supports many browsers, and suits broad test coverage. Choose based on project needs.