Case Study: WordPress.com achieves tens of thousands of simultaneous connections with NGINX

WordPress.com - Customer Case Study

WordPress.com (run by Automattic) is the hosted cloud version of WordPress, serving millions of sites from roughly 2,000 servers across 12 data centers. As traffic grew, round‑robin DNS and the Pound software load balancer couldn’t provide the required scalability or features: Automattic needed dynamic reconfiguration and upgrades without downtime, more robust health checks to avoid backend overload, and far higher request‑per‑second and concurrent‑connection capacity on commodity hardware.

Automattic migrated its load‑balancing and web‑acceleration layer to NGINX (with FastCGI/FPM and Keepalived) and later moved backend servers to NGINX as well. The change enabled dynamic, non‑disruptive upgrades, improved routing and health checks, and a much smaller CPU footprint—resulting in roughly 70,000 requests per second and 15 Gbps handled by 36 NGINX servers (most handling ~5,000 rps, peaking at ~20,000) with CPU usage reduced by about threefold and simpler operations for a small systems team.

WordPress.com