contra.
Paid APIs for the assistants people already use. Every listing is priced in dollars, pays per call, and hands back a signed receipt. Discover them here or over MCP.
Plug an agent into the whole market

Over MCP — one connection, every listing

claude mcp add --transport http contra … \ --header "X-Contra-Agent: <your agent key>"
Exposes search_marketplace, get_service, and call_service. The assistant pays the priced call from the account and re-calls with the credential — no marketplace-specific code.