> ## 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 crypto-to-crypto, fiat-to-crypto, and crypto-to-fiat money movement across ACH, wire, SWIFT, cash, and card rails. OMS infers the direction (`sourceToDestination`) from the instruments on each side of a transaction.

<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 full resource model: customers, wallets, quotes, transactions, cash-ins, virtual accounts, deposit addresses, counterparties, 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="Payouts & B2B" icon="users" href="/payments/use-cases/payroll-disbursements">
    Pay contractors, suppliers, and recipients from a single treasury wallet, via bank rails or cash pickup.
  </Card>

  <Card title="On- & off-ramps" icon="arrow-right-arrow-left" href="/payments/use-cases/consumer-on-offramp">
    Fund a wallet with cash or bank rails, hold a USDC balance, and withdraw back to a bank account.
  </Card>

  <Card title="Rewards & loyalty" icon="gift" href="/payments/use-cases/rewards-loyalty">
    Drop USDC rewards and cashback straight into user wallets. No card networks, no breakage, no expiry.
  </Card>

  <Card title="Cross-border send" icon="globe" href="/payments/use-cases/cross-border-remittance">
    Fiat in one country, fiat delivered in another, settled via Polygon in seconds.
  </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 whose `endorsements` (`basic`, `cryptoCustody`, `usd`) gate 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. Created under a customer with `POST /customers/{customerId}/wallets`. 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. OMS infers the direction (`sourceToDestination`) from the instruments. 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 transaction on confirmation.
  </Card>

  <Card title="Webhooks" icon="bell" href="/payments/transactions">
    Subscribe to events as they happen. Full CRUD: create, list, update, and delete subscriptions with `POST/GET/PATCH/DELETE /webhooks`, or manage them in the OMS Dashboard.
  </Card>
</CardGroup>

### Deposit and payout resources

These resources extend the core model with reusable deposit configurations and off-platform funding and payout references. You create and manage them directly through the API.

<Note>
  Transactions reference these resources by ID; when funds arrive at a deposit address or virtual account, OMS auto-creates the transaction. Deposit addresses must be enabled for your project: [contact us](https://info.polygon.technology/get-early-access?utm_source=docs\&utm_medium=note\&utm_campaign=oms_access) to enable them.
</Note>

<CardGroup cols={2}>
  <Card title="Virtual accounts" icon="landmark" href="/payments/guides/virtual-accounts">
    A dedicated bank account number assigned to a customer. Incoming fiat auto-converts to a stablecoin at the configured destination. Create and manage with `POST/GET/PATCH/DELETE /virtual-accounts`.
  </Card>

  <Card title="Deposit addresses" icon="arrow-down-to-bracket" href="/payments/guides/deposit-addresses">
    A reusable onchain address for a customer. Incoming crypto auto-triggers a transaction to a registered bank account. Create and manage with `POST/GET/PATCH /deposit-addresses`.
  </Card>

  <Card title="External accounts" icon="building-columns" href="/api-reference/guide-bank-transfers">
    Off-platform banks, external wallets, and cards. Register them with `POST /external-accounts` and reference them by `ext_` ID as a quote source or destination.
  </Card>

  <Card title="Counterparties" icon="handshake" href="/api-reference/guide-bank-transfers">
    A third party that is not your customer but owns external accounts you pay, for example a vendor. Full CRUD via `/counterparties`.
  </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 48 US states and international corridors