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Kono API Gateway

Kono is a lightweight, extensible API Gateway written in Go. It simplifies request routing, fan-out to multiple upstream services, and response aggregation — while remaining fast, predictable, and easy to configure.

Kono focuses on explicit configuration, minimal runtime overhead, and clear separation of concerns between routing, middleware, plugins, and upstream policies.

Key Features​

  • High-performance Go core — built with simplicity and low latency in mind
  • Multiple upstreams per route — dispatch requests to several services in parallel and aggregate their responses
  • Flexible aggregation strategies — merge, array, and namespace-based aggregation
  • Path parameter extraction — native {param} support with automatic forwarding to upstreams
  • Pluggable architecture — extend behavior using dynamically loaded .so plugins and middlewares
  • Fine-grained upstream policies — retries, circuit breaker, load balancing, timeouts, body limits, header filtering
  • OpenTelemetry observability — metrics (Prometheus or OTLP) and distributed tracing (OTLP) with W3C trace context propagation
  • Rate limiting & trusted proxy support
  • Declarative YAML configuration

Typical Use Cases​

  • API composition / Backend-for-Frontend (BFF)
  • Fan-out and aggregation of microservice responses
  • Centralized request validation and transformation
  • Edge gateway for internal services
  • Lightweight alternative to large API gateway solutions

Design Philosophy​

Kono aims to be:

  • Small, not bloated — only core gateway responsibilities
  • Explicit, not magical — behavior is visible in configuration
  • Composable — features are built from simple primitives
  • Observable by default — metrics, traces, and request IDs are first-class, not afterthoughts