Network Interception with Playwright TypeScript

Mohammad Faisal Khatri

14 min read

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Aug 11, 2026

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Playwright Network Interception: A Practical Guide to API Mocking, Request Modification, and Network Control

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Modern web applications rely heavily on APIs to fetch data, submit forms, authenticate users, and drive dynamic UI behavior. For test automation, however, relying entirely on real backend services can make tests slow, unreliable, and difficult to reproduce.

Playwright’s network interception capabilities provide a powerful way to control, inspect, and manipulate network traffic directly within automated tests. This tutorial covers the following topics:

1. What is Network Interception?
2. How Network Interception Works in Playwright
3. Monitor network traffic
4. How to fully mock an API Response without hitting the real server
5. Modify Request Headers or Body
6. Modify a Real API Response
7. Block Resources (Images, CSS, Analytics)
8. Simulate Network Failures & Slow Responses
9. Record & Replay with HAR Files
10. Debug Intercepted Requests with Trace Viewer
11. Best Practices