# Penny Engine
> Free deterministic tools for agents; no API key, no payment.

Website: https://penny-agent-api-production.up.railway.app
OpenAPI: https://penny-agent-api-production.up.railway.app/openapi.json
Remote MCP: https://penny-agent-api-production.up.railway.app/mcp
Tool catalog: https://penny-agent-api-production.up.railway.app/tools
AgentCash one-command quickstart: https://penny-agent-api-production.up.railway.app/agentcash-quickstart.md
Machine-installable configuration: https://penny-agent-api-production.up.railway.app/agent-install.json
Agent task-to-paid-API decision: POST https://penny-agent-api-production.up.railway.app/api/choose-service
Free MCP decision tool: penny_choose_service
Buying guide: https://penny-agent-api-production.up.railway.app/agent-buying-guide.json
Categories: Commerce, Business, Marketing, Developer
Example REST request: POST https://penny-agent-api-production.up.railway.app/api/marketplace-profit with JSON {"salePrice":28,"productCost":11,"shippingCost":4}
Free API charges nothing; separate paid routes at https://penny-paid-batch-production.up.railway.app return x402 USDC payment challenges. Outside settlement unverified.