Case Study: Flagsmith achieves economical real-time flag updates with Fastly

Flagsmith - Customer Case Study

Flagsmith, a feature flag and remote config platform, needed a way to deliver real-time flag updates to millions of clients without relying on costly long polling or websockets. As its API traffic grew to billions of requests per month and bursts spiked sharply, Flagsmith turned to Fastly to help solve the scaling challenge with its Fastly CDN and edge capabilities.

Fastly implemented Server-Sent Events (SSE) with request collapsing to fan out a single update stream to many users, offloading the heavy lifting from Flagsmith’s servers. The result was economical, real-time flag delivery and a new customer-facing capability, while Fastly handled the vast majority of requests and reduced load on Flagsmith’s infrastructure.

Flagsmith

Gagan Trivedi

Senior Backend Engineer