Instrument payments, attribute spend and apply local budget policies with small Apache-2.0 building blocks. Add Harpd when the team needs shared controls and reconciliation.
Start local
Each component does one job well, runs without Harpd, and gives your team a clear path from a local proof of concept to production controls.
@harpd/observe
Capture the x402 payment lifecycle in any agent loop. Run locally first; forward events when you are ready.
npm install @harpd/observe @harpd/x402-logging-middleware
Add auditable logging around x402 requests without changing your agent architecture.
npm install @harpd/x402-logging-middleware @harpd/mcp-paid-tool-starter
Start an x402-gated MCP tool with a small working example that you can rename and ship.
npm install @harpd/mcp-paid-tool-starter @harpd/agent-budget-policy
Declare per-call, per-agent, per-endpoint and per-tool caps; evaluate each decision locally before payment.
npm install @harpd/agent-budget-policy @harpd/agent-transaction-audit-schema
Use a portable event shape for payment decisions, settlement evidence and audit trails in your own database.
npm install @harpd/agent-transaction-audit-schema The components stay local and yours. The hosted layer handles the shared operational work around them.