stellar-core

stellar-core is the node software for the Stellar payment network. Every computer that validates Stellar transactions runs it, agreeing with its peers on a shared ledger every five to seven seconds. Apache 2.0, free, and maintained by the Stellar Development Foundation. Most builders should not run it.

That is Stellar's own advice. A validator should not be used for data access or transaction submission. App developers want Stellar RPC or Horizon, which bundle a captive copy of Core, or a hosted RPC provider. Run stellar-core when you issue an asset on the network and want a vote in how it is governed.

Running a validator is real infrastructure. The documented spec is 8 vCPUs, 16 GB of RAM, and 100 GB of local NVMe, plus Postgres and mandatory NTP time sync. Stellar does not recommend Kubernetes for validators. Ubuntu LTS gets official packages, RPM distros do not. Becoming a Tier 1 organization means three geographically spread full validators at 99.9% uptime, and operators report roughly $160 to $1,800 a month for the three nodes.

The catch: nothing in the docs mentions payment for validating. You run one to secure your own asset, support decentralization, and vote on protocol upgrades. Publishing a history archive from a big cloud provider adds egress bills on top.