KrakenD

KrakenD is an open-source API gateway written in Go that enables developers to expose a single, cohesive API surface by composing multiple backend services. It acts as a reverse proxy in front of microservices, handling routing, aggregation, and transformation of requests and responses.

Configuration is declarative in a single config file (JSON or YAML). Each endpoint specification includes the URL path, supported HTTP methods, and a list of backends (upstream services) with their URLs and authentication requirements. KrakenD processes requests by issuing parallel calls to the configured backends, then aggregates and reshapes the results into a unified response. It supports various request and response transformations, such as filtering, renaming, and structuring fields to fit client expectations.

Key features include high performance and a stateless architecture, which suit cloud-native deployments. It provides request and response transformations, endpoint aggregation, caching, and rate limiting. KrakenD also supports middleware-like capabilities for authentication, CORS, and logging, along with observability through metrics and logs. The project emphasizes simplicity and speed, with a design that facilitates rapid composition of APIs from heterogeneous services.

Deployment and ecosystem: KrakenD is designed for containerized environments and can be run in Docker and Kubernetes. It fits into modern CI/CD pipelines as a gateway layer that consolidates multiple services behind a single API surface.

Licensing and editions: The KrakenD Community Edition is released under an open-source license (Apache 2.0). A commercial Pro Edition provides additional features, enhanced security controls, analytics, and enterprise support. KrakenD is hosted and documented on its official site and GitHub repository.