Linkerd is a transparent proxy that can be used to extend microservices applications with service discovery, routing, error handling and monitoring functionalities. Now Linkerd has been released in version 2.1.
Linkerd is probably Kubernetes' second most common service mesh, and its architecture closely resembles Istio's, with an initial emphasis on simplicity rather than flexibility, due to its rewrite in v2. This reality results in less moving parts, along with it being a Kubernetes-only solution, which means that overall, Linkerd has less complexity. While Linkerd v1.x is still supported and supports more container frameworks than Kubernetes, the focus is on v2 with new features (such as blue/green deployments). Mostly.
Linkerd is unusual in that it is aware of the organisation responsible for Kubernetes, the Cloud Native Foundation (CNCF). No other service mesh is funded by an independent foundation.