> ## Documentation Index
> Fetch the complete documentation index at: https://docs.polygon.technology/llms.txt
> Use this file to discover all available pages before exploring further.

# Open Money Stack Payments API

> Open Money Stack Payments API: fiat-to-crypto and crypto-to-fiat on-ramps, custodial wallets, compliance, and stablecoin orchestration in a single integration. ACH, wire, SWIFT, cash, and card rails.

The Open Money Stack (OMS) Payments API moves money between fiat and stablecoins. It provides the full infrastructure stack: identity, custodial wallets, compliance, and fiat rail access, all integrated so they hand off cleanly to each other. One integration covers `fiatToCrypto`, `cryptoToFiat`, and `cryptoToCrypto` transactions across ACH, wire, SWIFT, cash, and card rails.

<CardGroup cols={2}>
  <Card title="Get started" icon="rocket" href="/payments/get-started">
    Onboard a customer, provision a wallet, and make your first transaction.
  </Card>

  <Card title="API reference" icon="book-open" href="/api-reference/overview">
    Full endpoint reference: transactions, quotes, wallets, customers, webhooks.
  </Card>
</CardGroup>

***

## Core concepts

<CardGroup cols={3}>
  <Card title="Entities & relationships" icon="diagram-project" href="/payments/core-concepts/entities">
    The core resources (customers, wallets, quotes, transactions, and cash-ins), the early-access concepts (virtual accounts, deposit addresses, and external accounts), and how they relate.
  </Card>

  <Card title="Quote system" icon="receipt" href="/payments/core-concepts/quote-system">
    How OMS locks pricing, structures fees, and calculates exchange rates before you commit to a transaction.
  </Card>

  <Card title="Account model" icon="wallet" href="/payments/core-concepts/account-model">
    Custodial wallets, virtual bank accounts, deposit addresses, and external accounts.
  </Card>

  <Card title="Transaction lifecycle" icon="repeat" href="/payments/core-concepts/transaction-lifecycle">
    Statuses, sub-statuses, webhook events, and auto-created transactions from deposit flows.
  </Card>

  <Card title="Currencies & rails" icon="coins" href="/payments/core-concepts/currencies-and-rails">
    Supported assets, networks, and fiat rails: ACH, SEPA, PIX, UPI, SPEI, cash networks, and stablecoins.
  </Card>
</CardGroup>

***

## Use cases

Common products built on the Open Money Stack. Each card links to a step-by-step walkthrough.

<CardGroup cols={3}>
  <Card title="Dollar accounts" icon="building-columns" href="/payments/use-cases/dollar-accounts">
    Give users a real USD account number that receives ACH transfers and holds a stablecoin balance.
  </Card>

  <Card title="On-ramp via cash" icon="money-bill-wave" href="/payments/use-cases/cash-funding">
    Fund a digital wallet with physical cash at retail locations.
  </Card>

  <Card title="Consumer on-ramp and off-ramp" icon="arrow-right-arrow-left" href="/payments/use-cases/consumer-on-offramp">
    Fund a wallet with cash-in, hold a USDC balance, and withdraw to a bank account.
  </Card>

  <Card title="Payroll and disbursements" icon="users" href="/payments/use-cases/payroll-disbursements">
    Pay contractors and employees in local currency from a single treasury wallet.
  </Card>

  <Card title="Cross-border remittance" icon="globe" href="/payments/use-cases/cross-border-remittance">
    Fiat in one country, fiat delivered in another, settled via Polygon in seconds.
  </Card>

  <Card title="Cash disbursements" icon="hand-holding-dollar" href="/payments/use-cases/cash-disbursement">
    Convert a wallet balance to physical cash via retail or ATM pickup codes.
  </Card>
</CardGroup>

***

## OMS primitives

The OMS API is managed through a core set of resources. Every transaction, deposit, and disbursement is built from these.

<CardGroup cols={2}>
  <Card title="Customers" icon="user" href="/payments/guides/customer-onboarding">
    An identity record with KYC endorsements that gates access to financial operations. Every wallet belongs to a customer.
  </Card>

  <Card title="Wallets" icon="wallet" href="/payments/guides/customer-onboarding">
    Custodial or non-custodial stablecoin balances on Polygon. Source or destination for any transaction.
  </Card>

  <Card title="Quotes" icon="receipt" href="/payments/guides/fiat-to-crypto">
    A rate lock with full fee breakdown. Created before every transaction. Expires if not executed within the validity window.
  </Card>

  <Card title="Transactions" icon="bolt" href="/payments/guides/crypto-to-fiat">
    Execute a quoted money movement: fiatToCrypto, cryptoToFiat, or cryptoToCrypto. Track status via webhooks through processing to completed.
  </Card>

  <Card title="Cash-ins" icon="shop" href="/api-reference/guide-cash-in">
    A code-based deposit flow for in-person cash funding at retail locations. Auto-creates a fiatToCrypto transaction on confirmation.
  </Card>

  <Card title="Webhooks" icon="bell" href="/payments/transactions">
    Subscribe to status changes across customers, transactions, and cash-ins. Full create, read, update, and delete support.
  </Card>
</CardGroup>

### Early-access concepts

The following are part of the OMS model but are not yet available in the OMS API. They are referenced as inputs in quote and transaction bodies today.

<CardGroup cols={2}>
  <Card title="Virtual accounts" icon="landmark" href="/payments/guides/virtual-accounts">
    A dedicated US bank account number assigned to a customer. Incoming ACH deposits auto-convert to USDC.
  </Card>

  <Card title="Deposit addresses" icon="arrow-down-to-bracket" href="/payments/guides/deposit-addresses">
    A persistent onchain address for a customer's wallet. Incoming crypto auto-triggers a transaction.
  </Card>

  <Card title="External accounts" icon="building-columns" href="/api-reference/guide-bank-transfers">
    A customer's bank account, referenced by ID as a destination for off-ramps. Early access.
  </Card>
</CardGroup>

***

## Why Polygon for settlement

* **Sub-2-second finality** with 99.9%+ network uptime
* **\$0.002 average transaction cost** on Polygon Chain
* **\$54B+ in stablecoin transfer volume** processed onchain
* **Native USDC**: no wrapping, no bridging, no surprise deductions
* **Compliance included**: KYC, KYB, AML screening, and transaction monitoring across 38 US states and international corridors