Break Free from ESI Lock-in: Learn How to Migrate Today with Fastly

Edge Side Includes (ESI) was introduced in the early 2000s by Akamai to help developers manage dynamic content at the network edge, enhancing performance and reducing server load, but it never achieved standardization and became proprietary, leading to vendor lock-in for many organizations. Fastly has now developed a new ESI implementation powered by Fastly Compute, which not only replicates Akamai's native ESI features but also provides additional capabilities such as control flow, error handling, variables, and complex data types. This new implementation offers a high-performance engine that allows ESI tags to run on Fastly’s global network, facilitating the transition from static templates to fully programmable edge logic. Although ESI was never designed for the complexity of modern web applications, Fastly's solution allows organizations to maintain existing ESI functionality while incrementally refactoring workloads into more advanced languages like Rust or JavaScript, opening the door to modern features like passwordless authorization and edge-rate limiting.