How does a reverse proxy like Varnish work?

A reverse proxy sits in front of the actual web server and keeps complete HTML pages in memory. When a visitor requests an already cached page, the proxy serves it directly from RAM, without PHP being executed or the database even being queried. This brings the TTFB down to a few milliseconds, even for elaborately generated dynamic pages, and at the same time relieves the server during load spikes.

Varnish is therefore especially effective for Shopware shops with many category and product pages that change only rarely. The challenge lies in clean cache invalidation: a price change or an empty stock level must take effect immediately, while everything else stays in the cache. We configure exactly these rules per project, so that speed does not come at the expense of timeliness.