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Documentation Index

Fetch the complete documentation index at: https://docs.crossmint.com/llms.txt

Use this file to discover all available pages before exploring further.

Agents operate across two distinct economies:
  • The traditional web runs on cards. Amazon, Shopify stores, SaaS checkouts, and most traditional merchants rely on card payments. Users expect familiar properties like card rewards, refunds, and chargebacks.
  • The agentic web runs on stablecoins. x402 and MPP-gated APIs, micropayments, and machine-to-machine settlement require stablecoins. Cards don’t work here since fees, chargebacks, and merchant account constraints make small or programmatic payments impractical.
Most agents need both so Crossmint provides cards and stablecoin wallets as first-class primitives.

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Payment methods need spending rules

You cannot give an agent unrestricted access to money:
  • Credentials can be leaked
  • Agents can overspend or behave unexpectedly
An agent with unlimited access is a liability. The goal is not just “agents can pay”, it is “agents can pay securely without exposing sensitive data.” Each payment method enforces this differently:
  • Card agentic protocols. The user’s real card is stored in a PCI-compliant vault. Users give agents permissions to use their card with spending rules (amount, merchant, duration), enforced at the network level via Visa VIC and Mastercard Agent Pay. The agent never sees the real card number — developers never handle sensitive information.
Diagram: a user verifies their card once via Visa VIC or Mastercard Agent Pay, and agents receive scoped permissions with spending rules
  • Wallet non-custodial delegation. The user owns the wallet and grants the agent scoped permissions (spend limit, counterparties, time window). Developers and agents never take custody of funds.

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User flows

Every payment method an agent uses is set up through a user flow — a hosted, customizable UI where the user explicitly delegates access. The flows below cover the end to end integration steps for both cards and wallets. One principle holds across all of them: the user stays in control. Every delegation is explicit, scoped, and revocable. Crossmint provides the UI components and signing flows. You wire them into your product.
1

User saves a card

Via a Crossmint-hosted secure iframe.
2

User verifies the card for agentic use

This step links the card to the agentic card rails.
  • Happens in a Crossmint component
  • User verifies ownership (e.g. email code or bank auth)
  • A passkey is created for future approvals
3

The user sets spending rules and allows payment

The developer requests a card permission with spending rules (amount, merchant, expiration). A network modal (Visa/Mastercard) appears and the user confirms using their passkey.
4

Agent pays using a secure card number

Each approved payment returns a secure one-time card number that only works within the spending rules — never the real card number. The agent uses it in browser checkout or APIs.

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How agents actually pay

Once setup is complete, agents can spend. The payment flow depends on where they are paying.
FlowPayment methodHow it worksBest for
x402StablecoinAgent calls an endpoint, receives 402 Payment Required, pays in stablecoin, retriesPay-per-call APIs, micropayments
MPPStablecoinAgent-to-agent and service-to-service payments over a payment protocolProgrammatic machine economies
Browser CheckoutCardAgent drives a real browser and fills checkout forms using a secure card numberAny website that accepts cards
Fast CheckoutCard or stablecoinA single API call replaces the entire checkout flow — no browser neededAmazon, Shopify stores (US only)

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Choose Your Path

Cards quickstart

Build an agent paying with card permissions.

Wallets quickstart

Build an agent paying with stablecoins.