Apply for Melio partner API access through the Melio partners program; API access requires at least the Platinum-tier agreement
Authenticate using the API credentials provided by Melio and pass them in the Authorization header per the partner API documentation
Create or sync vendor records and bill data into Melio, mapping amounts, due dates, and payment methods (ACH, virtual card, or check)
Initiate payment scheduling for a bill, selecting the customer's preferred funding source (bank account or credit card)
Receive payment confirmation and reconciliation data via webhook or polling, then sync status back to the connected ERP (QuickBooks or Xero)
Known gotchas
Melio's public API is partner-gated; direct developer access is not available without a formal partner agreement — factor this into integration timelines
Virtual card payments to vendors are issued by Melio; the vendor receives a one-time card number and must manually charge it, which not all vendors support
Cross-platform sync with QuickBooks or Xero is bidirectional but requires OAuth consent from the end customer, not just the platform
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp