Case Study: Transport for London achieves faster, more resilient journey planning and 30% hosting cost savings with Varnish Software

Varnish Helps TFL Prevent Web Traffic Jams And Better Serve London’s Commuters

Transport for London (TfL) runs the capital’s transport network information used by roughly 10 million unique website users a month (about 81% of commuters) and delivers 1.2 billion pages a year, with 80% of content dynamic and traffic able to spike up to 50× during incidents. As smartphone use overtook desktop and customers demanded more personalization and real‑time journey planning, TfL needed to replace its legacy CDN-based architecture to improve performance, resilience and mobile experience.

TfL rebuilt its site on a cloud platform with Varnish as a high-availability front-end cache (launched March 2014), enabling instant, personalized responses for web and third‑party apps. The new architecture handled a 2 million‑visit strike day easily, cut hosting costs by about 30%, increased customer satisfaction to 86% and grew journey planning by 10%; today it serves ~7 million API requests daily with >90% cache hits and supports 6,000+ app developers.

Transport for London

Phil Young

Head of Online