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

# Supported chains and assets

> Blockchains, stablecoins, and base assets Bastion supports across EVM and SVM mainnets and testnets, with chain IDs and block explorers.

Bastion supports multiple blockchain networks across different chain families, enabling cross-chain stablecoin custody, transfers, and conversions.

## Supported mainnets

The following mainnet networks are fully supported in production:

### EVM chains

| Chain    | Chain ID | Label        | Base Asset | Decimals | Block Explorer          |
| -------- | -------- | ------------ | ---------- | -------- | ----------------------- |
| Ethereum | 1        | Ethereum     | ETH        | 18       | etherscan.io            |
| Polygon  | 137      | Polygon      | POL        | 18       | polygonscan.com         |
| Base     | 8453     | Base Mainnet | ETH        | 18       | basescan.org            |
| Optimism | 10       | Optimism     | ETH        | 18       | optimistic.etherscan.io |

### SVM chains

| Chain  | Label          | Base Asset | Decimals | Block Explorer      |
| ------ | -------------- | ---------- | -------- | ------------------- |
| Solana | Solana Mainnet | SOL        | 9        | explorer.solana.com |

## Supported testnets

The following testnet networks are available for development and testing:

### EVM testnets

| Chain            | Chain ID | Label            | Base Asset | Block Explorer                |
| ---------------- | -------- | ---------------- | ---------- | ----------------------------- |
| Ethereum Sepolia | 11155111 | Sepolia          | ETH        | sepolia.etherscan.io          |
| Polygon Amoy     | 80002    | Polygon Amoy     | POL        | amoy.polygonscan.com          |
| Base Sepolia     | 84532    | Base Sepolia     | ETH        | sepolia.basescan.org          |
| Optimism Sepolia | 11155420 | Optimism Sepolia | ETH        | sepolia-optimism.etherscan.io |

### SVM testnets

| Chain         | Label         | Base Asset | Block Explorer      |
| ------------- | ------------- | ---------- | ------------------- |
| Solana Devnet | Solana Devnet | SOL        | explorer.solana.com |

## Chain identifiers

Each chain is referenced using a standardized enum value:

| Mainnet Enum       | Testnet Enum       |
| ------------------ | ------------------ |
| `ETHEREUM_MAINNET` | `ETHEREUM_TESTNET` |
| `POLYGON_MAINNET`  | `POLYGON_AMOY`     |
| `BASE_MAINNET`     | `BASE_SEPOLIA`     |
| `OPTIMISM_MAINNET` | `OPTIMISM_SEPOLIA` |
| `SOLANA_MAINNET`   | `SOLANA_DEVNET`    |

## Chain families

Bastion groups blockchains into families based on their underlying virtual machine architecture:

| Chain Family | Identifier         | Description                                |
| ------------ | ------------------ | ------------------------------------------ |
| EVM          | `CHAIN_FAMILY_EVM` | Ethereum Virtual Machine compatible chains |
| SVM          | `CHAIN_FAMILY_SVM` | Solana Virtual Machine compatible chains   |

## Supported stablecoins

Bastion provides support for the following stablecoins.

| Asset | Ethereum | Polygon | Base | Optimism | Solana |
| ----- | -------- | ------- | ---- | -------- | ------ |
| USDC  | Yes      | Yes     | Yes  | Yes      | Yes    |
| USDT  | Yes      | No      | No   | No       | No     |

## On/off-ramp conversions support

Custody and crypto transfers work on every chain above. Conversions work on a subset, and the subset depends on the direction and jurisdiction.

| Conversion             | Chains                          | Stablecoins                |
| ---------------------- | ------------------------------- | -------------------------- |
| US On-ramp             | Ethereum, Solana, Base          | USDC                       |
| US off-ramp            | Ethereum, Solana, Base          | USDC, and USDT on Ethereum |
| International off-ramp | Ethereum, Solana, Base, Polygon | USDC                       |

Optimism supports custody and transfers only. 

For payout countries, currencies, and rails supported for off-ramps, see [Supported off-ramp payout countries.](/guides/getting-started/supported-off-ramp-payout-countries)

## Base assets and gas

Bastion sponsors gas by default on all supported chains. Your customers do not need to hold native tokens to send transfers; Bastion covers transaction fees automatically. Gas sponsorship is opt-out, not opt-in. If you need to disable it, contact your Bastion account team.

If gas sponsorship is disabled, wallets will need to hold the chain's native asset to cover network fees:

| Asset  | Symbol | Decimals | Chains                   |
| ------ | ------ | -------- | ------------------------ |
| Ether  | ETH    | 18       | Ethereum, Base, Optimism |
| POL    | POL    | 18       | Polygon                  |
| Solana | SOL    | 9        | Solana                   |

Base assets are not available for conversions or other value-transfer services. Bastion's custody and conversion products are built around stablecoins.

## Wallet address support

Bastion automatically generates wallet addresses for supported chain families:

| Chain Family | Address Format                     | Example                                    |
| ------------ | ---------------------------------- | ------------------------------------------ |
| EVM          | 40 hex characters with `0x` prefix | `0x742d35Cc6634C0532925a3b844Bc9e7595f...` |
| SVM          | Base58 encoded public key          | `7EcDhSYGxXyscszYEp35KHN8vvw3svAuLKT...`   |

Each account receives addresses for both EVM and SVM chain families, enabling multi-chain operations.

## Environment behavior

Chain availability is environment-dependent:

| Environment           | Available Chains      |
| --------------------- | --------------------- |
| Production            | Mainnets and Testnets |
| Sandbox / Development | Testnets only         |

Mainnet chains are only accessible in the production environment. Development and sandbox environments use corresponding testnets.

## Coming soon

### USDT for international off-ramps

In development. USDT is supported for US off-ramps on Ethereum today.

### Avalanche

Avalanche C-Chain support is currently in development:

| Chain             | Chain ID | Label          | Base Asset | Decimals | Status         |
| ----------------- | -------- | -------------- | ---------- | -------- | -------------- |
| Avalanche C-Chain | 43114    | Avalanche      | AVAX       | 18       | In development |
| Avalanche Fuji    | 43113    | Avalanche Fuji | AVAX       | 18       | In development |

## API chain parameters

When making API calls, use the chain enum values:

```JSON theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
{
  "chain": "SOLANA_MAINNET"
}
```

<br />


## Related topics

- [Send crypto on-chain to any wallet address](/guides/quickstarts/send-crypto/on-chain.md)
- [Off-ramp: Withdraw stablecoin internationally](/guides/quickstarts/off-ramp/international-bank-account.md)
- [Off-ramp: Withdraw stablecoin to a US bank account](/guides/quickstarts/off-ramp/withdraw-to-a-bank-account.md)
- [Crypto transfers and deposits](/guides/concepts/crypto-transfers.md)
- [Crypto custody](/guides/concepts/custody.md)