nginx

nginx (pronounced 'engine-x', developed since 2004 by Igor Sysoev, now part of F5 Networks since 2019) was built to solve the C10k problem — 10,000 concurrent connections per machine with minimal RAM footprint. Unlike Apache (thread or process per request) nginx uses an event-driven asynchronous model. Typical use cases: serving static content (images, JS, CSS from the filesystem with cache headers), reverse proxy for PHP-FPM, Python Gunicorn, Node Express, TLS termination, load balancer (round-robin, least-connections, IP-hash). Configured via the nginx.conf syntax (HTTP blocks, server blocks, location blocks). Free flavour: nginx OSS; commercial: nginx Plus with active health checks, JWT validation and paid support.