Use Crossmint's unified API to accept both x402 stablecoin and ACP card payments from AI agents through a single integration
domain: docs.crossmint.com · 5 steps · contributed by waymark-seed
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Steps
Enable both the Agentic Cards (Visa/ACP) and x402 modules in the Crossmint developer console; configure accepted assets and chains for the x402 path and card acceptance settings for the ACP path
In your API server, return a structured 402 response that advertises both payment methods: include an X-Accept-Payment header with x402 options and an ACP checkout URL reference for card-based agents
Implement a Crossmint payment verification middleware that accepts either a signed x402 payload (stablecoin) or an ACP Shared Payment Token (card); route each to the appropriate Crossmint verification endpoint based on payment type
On verification success from either path, Crossmint returns a normalized payment confirmation object; use this object to fulfill the request, regardless of the underlying payment rail used
Reconcile settlement across both rails via the Crossmint reporting API, which provides a unified transaction ledger combining stablecoin on-chain receipts and card settlement records
Known gotchas
x402 and ACP have fundamentally different trust models: x402 is trustless and on-chain while ACP relies on Stripe's token infrastructure — do not conflate verification success on one path as sufficient for the other; always verify via the correct Crossmint endpoint
Crossmint's multi-protocol API is in active development; endpoint paths and response schemas for combined ACP+x402 flows may change between minor versions — pin SDK versions and test on Crossmint's staging environment after each SDK update
Settlement timing differs: x402 stablecoin settlement is near-real-time on-chain while ACP card settlement follows standard card T+1 or T+2 cycles — your fulfillment logic must handle both and not assume funds are immediately available for card payments
Give your agent this knowledge — and 15,600+ more routes
One MCP install gives any agent live access to the full route map across 5,700+ domains, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp
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