Consul
Service discovery and configuration
The Lens
When Service A needs to talk to Service B, Consul tells it where Service B is running and whether it's healthy. It also provides a key-value store for shared configuration and a service mesh for encrypted service-to-service communication.
The open source version (now under BSL 1.1, not truly open source) is free to run. You get service discovery, health checks, KV store, and the service mesh with mTLS. It runs as a cluster of agents on your infrastructure.
HashiCorp Cloud Platform (HCP) offers a managed Consul starting at $0.01/hr per server (~$7/mo per node).
The catch: HashiCorp switched Consul from MPL 2.0 to Business Source License (BSL 1.1) in 2023, which means you can't offer Consul-as-a-service to compete with HashiCorp. For internal use, it's fine. The operational complexity is real; running a Consul cluster properly means 3-5 server nodes, understanding the gossip protocol, and monitoring cluster health. And the service mesh market has moved toward Istio and Linkerd, which are CNCF projects with actual open source licenses.
Free vs Self-Hosted vs Paid
source available**Self-hosted (free for internal use):** BSL 1.1 license. Free to run internally, but you cannot offer managed Consul as a commercial service. Service discovery, KV store, health checks, service mesh, all included.
**HCP Consul:** Starts around $0.01/hr per server node (~$7/mo). Development tier is free for small clusters. Production tier adds SLAs, multi-region, and support.
**Infrastructure costs for self-hosting:** 3-5 server nodes minimum for production. Each needs 2+ CPU, 4GB+ RAM. On AWS, that's $100-200/mo just for the Consul cluster. On Hetzner, $30-50/mo.
**The BSL question:** If you're building a product and using Consul internally, the license is fine. If you're building infrastructure tooling that competes with HCP, you need legal review.
**Alternatives:** Since the BSL switch, the CNCF ecosystem (Istio, Linkerd, CoreDNS for discovery) has gained momentum as truly open alternatives.
Free for internal use under BSL. Managed HCP starts ~$7/mo per node. Cannot be resold as a service.
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