```yaml
product: AlterLab
title: "Caching — Web Scraping Glossary | AlterLab"
comparison_context: "AlterLab is an alternative to Firecrawl, ScrapingBee, and Bright Data."
source_url: https://alterlab.io/glossary/caching
```

protocol

# Caching

Storing copies of web responses to serve repeat requests faster, which can cause scrapers to receive stale data instead of live content.

Caching is the storage of a copy of a web response so that subsequent identical requests can be served from the cache rather than regenerated by the origin server. Caches exist at multiple levels in the web stack: the origin server (application-level caching with Redis or Memcached), the CDN edge (HTTP caching based on Cache-Control and Vary headers), the browser (local cache), and proxy caches in between.

For web scraping, caching creates two distinct problems. First, cached responses may be stale — a scraper retrieving prices or inventory may receive data from a cached response that is hours or days old rather than the current live data. Cache headers (`Cache-Control: max-age=86400`, `Expires`) indicate the intended freshness window. Second, cached responses bypass some anti-bot checks — a CDN serving a cached response from its own infrastructure may not trigger the same bot detection as a live origin request.

Strategies for bypassing caches to receive live data include: adding a random query parameter (`?_t=<timestamp>`) to prevent cache key matching, using cache-busting headers (`Cache-Control: no-cache`, `Pragma: no-cache`), or submitting POST requests rather than GETs (POST responses are typically not cached). AlterLab passes cache-control headers that request fresh responses from origins.

### What is Caching?

Storing copies of web responses to serve repeat requests faster, which can cause scrapers to receive stale data instead of live content.

### How does AlterLab handle Caching?

Strategies for bypassing caches to receive live data include: adding a random query parameter (`?_t=<timestamp>`) to prevent cache key matching, using cache-busting headers (`Cache-Control: no-cache`, `Pragma: no-cache`), or submitting POST requests rather than GETs (POST responses are typically not cached). AlterLab passes cache-control headers that request fresh responses from origins.

## Related Terms

[Content Delivery Network (CDN)A distributed network of servers that delivers web content from locations geographically close to the user, often where anti-bot protection is deployed.](https://alterlab.io/glossary/content-delivery-network)[HTTP HeadersKey-value metadata fields sent with HTTP requests and responses that communicate authentication, content type, caching, and other directives.](https://alterlab.io/glossary/http-headers)[Web ScrapingAutomated extraction of data from websites using software tools that parse HTML and collect structured information at scale.](https://alterlab.io/glossary/web-scraping)[Rate LimitingA server-side control that caps the number of requests accepted from a single IP or session within a time window, returning HTTP 429 when exceeded.](https://alterlab.io/glossary/rate-limiting)

## Extract Caching data from any website

AlterLab returns clean, structured data from any public URL — no scraper infrastructure needed. Start free, no credit card required.

[View API docs](https://alterlab.io/docs/api/rest)

[Back to Glossary](https://alterlab.io/glossary)