> ## Documentation Index > Fetch the complete documentation index at: https://docs.mag3nt.com/llms.txt > Use this file to discover all available pages before exploring further. # Buy a listed credential > Escrows the buyer's USDC card funds, atomically re-keys credential ownership (and its pay links), pays out the seller net of the marketplace take rate, and captures the fee. Any failure after escrow fully unwinds - no half-completed sale, no lost funds. ## OpenAPI ````yaml /openapi.yaml post /api/listings/{id}/buy openapi: 3.1.0 info: title: mag3nt API version: '2026-07-16' description: > Payment infrastructure for AI agents. Issue virtual cards backed by credentials, pay for API access via x402/AP2/MPP protocols, and settle in USDC on Base. Also covers Native Token Rails membership and recurring billing agreements, ERC-20 project token registration (including B20) and prepaid MAG3NT fee metering for DIRECT (non-custodial) settlement, the credential marketplace and Credential Token (CT) markets, account-wide token holdings, and signed webhooks for payment and subscription lifecycle events. contact: name: mag3nt url: https://mag3nt.com license: name: Proprietary url: https://github.com/mag3nt-com/mag3nt-node/blob/main/LICENSE servers: - url: https://mag3nt.com description: Production - url: https://staging.mag3nt.com description: Staging, Base mainnet security: - ApiKeyAuth: [] tags: - name: Payments description: Universal outbound protocol payments - name: Cards description: Virtual payment card lifecycle - name: Keys description: Developer API key management - name: Funding description: Treasury deposits and balances - name: x402 description: HTTP 402 payment protocol - name: AP2 description: Agent-to-Agent Payment Protocol - name: MPP description: Micropayment Protocol with streaming - name: Pay Links description: Shareable payment URLs - name: Withdrawals description: Withdraw unspent funds back to wallet - name: Settlement description: On-chain settlement status - name: Webhooks description: Signed payment and subscription lifecycle notifications for sellers - name: Status description: System health and configuration - name: Membership description: Native Token Rails membership tiers, checkout, and auto-renew - name: Billing description: Recurring billing agreements funded by AP2 open mandates - name: Tokens description: >- Register an ERC-20 contract (including B20 tokens) for DIRECT credential settlement - name: Fees description: Prepaid MAG3NT fee meter for DIRECT settlement overage - name: Marketplace description: >- List and transfer credential businesses (proof of record) on the mag3nt marketplace - name: Credential Tokens description: Credential Token (CT) launch and Uniswap V4 markets - name: Holdings description: Account-wide Credential Token balances externalDocs: description: mag3nt documentation url: https://docs.mag3nt.com paths: /api/listings/{id}/buy: post: tags: - Marketplace summary: Buy a listed credential description: > Escrows the buyer's USDC card funds, atomically re-keys credential ownership (and its pay links), pays out the seller net of the marketplace take rate, and captures the fee. Any failure after escrow fully unwinds - no half-completed sale, no lost funds. operationId: marketplaceBuyListing parameters: - name: id in: path required: true schema: type: string requestBody: required: true content: application/json: schema: type: object required: - buyer_card_id properties: buyer_card_id: type: string description: An ACTIVE USDC card you own to pay from. responses: '200': description: Purchase settled content: application/json: schema: type: object properties: success: type: boolean listing: $ref: '#/components/schemas/Listing' feeQuote: type: object payoutTx: type: string '400': description: >- Pay card is not USDC, wrong network, or self-custody sale not yet supported content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: Pay card or listing not found content: application/json: schema: $ref: '#/components/schemas/Error' '409': description: Listing is not available (already sold/cancelled/encumbered) content: application/json: schema: type: object properties: error: type: string code: type: string example: NOT_LISTED components: schemas: Listing: type: object properties: id: type: string example: lst_mag3nt_abc123_1719500000000_42 card_id: type: string seller: type: string price: type: number currency: type: string enum: - USDC - magUSD description: Only USDC settlement is live today. status: type: string enum: - LISTED - CANCELLED - SOLD created_at: type: string format: date-time buyer: type: - string - 'null' settled_tx: type: - string - 'null' settled_at: type: - string - 'null' format: date-time sellable: type: boolean description: >- Mirrors the exact buy-time gate (LISTED, not frozen/seized/closed, not encumbered). Present on GET /api/listings/{id}. stats: $ref: '#/components/schemas/CredentialStats' Error: type: object required: - error properties: error: type: string example: Card not found CredentialStats: type: - object - 'null' description: >- Verifiable, ledger-derived performance for a credential. Never fabricated. properties: rxCount: type: integer rxLifetime: type: number rx30d: type: number rx30dCount: type: integer lastActive: type: - string - 'null' format: date-time firstActive: type: - string - 'null' format: date-time protocols: type: integer balance: type: number ageDays: type: - integer - 'null' hasCrt: type: boolean crtStatus: type: - string - 'null' crtAddress: type: - string - 'null' crtSymbol: type: - string - 'null' holderAddress: type: - string - 'null' chainStatus: type: - string - 'null' identityToken: type: - string - 'null' identityStatus: type: - string - 'null' securitySchemes: ApiKeyAuth: type: apiKey in: header name: Authorization description: API key prefixed with 'Bearer sx_live_...' ````