protocol

Cache Busting

Cache busting forces a fresh server request by adding a unique query parameter or modifying the URL so that cached responses are bypassed and current content is fetched.

HTTP caches and CDNs store responses keyed by URL. Adding a unique query parameter — a timestamp, random value, or content hash — to a URL effectively creates a new cache key, forcing every cache layer between the client and the origin server to fetch a fresh copy. This is useful when scraping content that changes frequently and must not be served stale from intermediate caches.

For scrapers monitoring content for changes, appending `?_t=` with the current Unix timestamp ensures each request goes to the origin. However, this also increases origin server load and may trigger rate limits — use sparingly and only when freshness is critical.

Cache busting is also used by web developers to force browsers to load updated JavaScript and CSS bundles after a deployment: the asset URL includes a content hash (`main.abc123.js`) that changes with each build, guaranteeing the browser fetches the new version rather than serving the cached old one.

Examples

import time, requests

# Force a fresh response by appending a timestamp parameter
url = f"https://example.com/prices?_nocache={int(time.time())}"
response = requests.get(url)