Consul

Consul is HashiCorp's Swiss Army knife for service networking — service discovery, health checking, KV store, and service mesh in one binary. In a microservices world where services come and go, Consul keeps track of what's running where.

If you're running distributed services and need them to find each other, Consul does the job. etcd is the alternative for pure KV and config storage (simpler, used by Kubernetes). ZooKeeper is the legacy option. Eureka from Netflix handles service discovery for Java shops. Commercially, cloud service discovery (AWS Cloud Map, GCP Service Directory) are simpler if you're single-cloud.

Consul Connect adds mTLS between services without code changes. The multi-datacenter support is genuinely useful for hybrid cloud setups.

The catch: HashiCorp moved Consul to the BSL license, which restricts competing hosted services from offering it. For internal use it's fine, but the community trust took a hit. Also, Consul tries to do everything — discovery, KV, mesh, DNS — and teams often end up using just one feature while paying the operational cost of the full platform. If you only need service discovery, something simpler (like DNS-based discovery in Kubernetes) might suffice.