Finagle is a fault-tolerant, protocol-agnostic RPC system for building high-concurrency servers on the JVM.
Finagle addresses the challenge of constructing distributed systems that handle high concurrency while remaining resilient to failures. It provides uniform client and server APIs across multiple protocols including HTTP, HTTP/2, Thrift, MySQL, Redis, and Memcached. The system is designed with protocol-agnostic core logic, which simplifies the addition of new protocols and allows developers to write fault-tolerance and concurrency handling code once rather than reimplementing it for each protocol.
Finagle suits teams building services that require robust RPC communication with high throughput and low latency. It works well for organizations already invested in the JVM ecosystem and Scala, though it is usable from Java as well. The tool is particularly valuable when you need to support multiple protocols within a single framework or when you want consistent patterns for handling timeouts, retries, load balancing, and circuit breaking across different service communication types. Finagle is production-tested at scale and adopted by numerous organizations running critical infrastructure.
The project maintains a regular release cadence with detailed changelogs that document public API breaks and runtime behavior changes. Development is active with ongoing maintenance and feature work. The community maintains multiple channels for engagement including a mailing list, chat platform, and blog. The project welcomes contributions and has established community guidelines for interactions.
