> ## 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.

# Currencies and rails

> Supported assets, networks, and payment rails in OMS.

Every side of a transaction specifies an **asset** (what kind of money) and a **network** (how it moves). The same field structure works for both crypto and fiat.

## Asset and network format

```json theme={null}
{
  "asset": "usdc",
  "network": "polygon"
}
```

All values are lowercase. The supported combinations are documented in the tables on this page.

## Crypto assets and networks

| Asset  | Network    | Description                                         |
| ------ | ---------- | --------------------------------------------------- |
| `usdc` | `polygon`  | USDC on Polygon Chain, the primary settlement asset |
| `usdc` | `ethereum` | USDC on Ethereum mainnet                            |
| `usdc` | `solana`   | USDC on Solana                                      |
| `btc`  | `bitcoin`  | Bitcoin                                             |
| `eth`  | `ethereum` | Ether                                               |

Polygon Chain is the recommended network for most use cases: sub-2-second finality, \$0.002 average transaction cost, and native USDC (no bridging or wrapping).

## Fiat rails

| Asset | Network | Description                                                |
| ----- | ------- | ---------------------------------------------------------- |
| `usd` | `ach`   | US dollars via ACH bank transfer                           |
| `usd` | `wire`  | US dollars via domestic wire                               |
| `usd` | `card`  | US dollars via debit card (coming soon)                    |
| `usd` | `cash`  | US dollars via physical cash (GreenDot / AllPoint network) |
| `eur` | `sepa`  | Euros via SEPA Instant                                     |
| `brl` | `pix`   | Brazilian reais via PIX                                    |
| `inr` | `upi`   | Indian rupees via UPI                                      |
| `mxn` | `spei`  | Mexican pesos via SPEI                                     |
| `gbp` | `fps`   | British pounds via Faster Payments                         |

<Note>
  Supported corridors and rails expand regularly. The tables on this page are the authoritative list.
</Note>

## Exchange rates and FX

When a transaction crosses currencies (e.g., USD to USDC, or USDC to EUR), OMS applies a live exchange rate at quote time. The quote response includes:

* `rates.exchangeRate`: the spot rate used
* `rates.effectiveRate`: the post-fee rate the customer actually receives
* `expiresAt`: when the locked rate expires

OMS sources liquidity from multiple venues and routes to minimize spread. The fee breakdown shows OMS fees, developer fees, and gas costs separately.

## Cash networks

Cash off-ramps use OMS's partnership with physical cash networks:

* **GreenDot**: US cash deposits and withdrawals at retail locations (CVS, Walgreens, Walmart)
* **AllPoint ATM**: Cash withdrawals across the AllPoint ATM network

Cash on-ramps generate a deposit code the customer presents at a retail location. OMS monitors for the deposit and auto-creates a `fiatToCrypto` transaction when cash is received. See [Cash-in guide](/api-reference/guide-cash-in) for the full flow.