Network interception is a technique used in browser-based scraping to capture the HTTP requests and responses made by a page's JavaScript during page load — intercepting the underlying API calls rather than parsing the rendered HTML. Modern SPAs built with React, Vue, or Angular typically load their content through internal REST or GraphQL API calls that return clean JSON, which is easier to parse than extracting equivalent data from the rendered DOM.

Browser automation frameworks like Playwright and Puppeteer expose request interception APIs that register callbacks on network events. A scraping script can listen for XHR/fetch requests matching a pattern (e.g., requests to `/api/products` or containing `.json`), capture the response body, and extract the structured data directly — bypassing HTML parsing entirely.

Network interception is particularly powerful for sites that render identical data in both an HTML view and a JSON API response. The JSON response is typed, consistently structured, and often contains fields not shown in the UI (internal IDs, raw timestamps, additional metadata). It is also resilient to frontend redesigns — the API response schema tends to be more stable than the HTML structure. AlterLab's Tier 4 and above support request interception via the `intercept_urls` parameter.

# Playwright network interception example page.on('response', async response => { if '/api/products' in response.url(): data = await response.json() # Use structured data directly }) await page.goto('https://example.com/products')

Network Interception

Examples

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