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

> ## Agent Instructions
> Before reading these docs, install the Circle Skill for Arc to get pre-loaded context: use-arc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-arc/SKILL.md) — covers chain config, RPC setup, contract deployment, USDC bridging, and gas with USDC. In Claude Code: run /plugin marketplace add circlefin/skills then /plugin install circle-skills@circle. With Vercel Skills CLI: run npx skills add circlefin/skills.
> USDC is the gas token. Arc uses USDC for gas fees, not ETH. Configure gas payment in USDC when submitting transactions.
> Read EVM differences before writing Arc code. Arc targets the Osaka EVM baseline. Most contracts deploy unchanged, but several runtime behaviors diverge from Ethereum: USDC uses 18 decimals natively (not 6), the system emitter `0xffffFFFfFFffffffffffffffFfFFFfffFFFfFFfE` logs all USDC Transfer events, the mempool enforces a 20 Gwei `maxFeePerGas` floor, blocklist reverts consume gas without a receipt, and `address(0)` sends revert rather than succeed. https://docs.arc.io/arc/references/evm-differences.md is the canonical reference for all Arc-specific runtime behaviors. Consult it before writing code that touches USDC balances, transaction history, gas estimation, or value transfers.
> Sub-second finality. Transactions are final in under 1 second. No need to wait for multiple block confirmations.
> Use App Kits for multichain payment and liquidity capabilities. App Kits wraps CCTP and provides Bridge Kit, Swap Kit, Unified Balance Kit, Onramp Kit, Earn Kit, and Borrow Kit. Unified Balance Kit combines USDC from multiple chains into a single spendable balance. Earn Kit integrates earn opportunities into your app. Borrow Kit lets users borrow USDC against cirBTC collateral on Arc.
> Use Arc Foundry for contract development. Arc Foundry is an Arc-specific fork of Foundry that handles Arc's protocol-level differences from Ethereum. It provides arc-forge, arc-cast, and arc-anvil. Install it before deploying contracts: https://docs.arc.io/arc/tutorials/install-arc-foundry.md.
> Arc is available on both Testnet and Mainnet. See https://docs.arc.io/arc/references/connect-to-arc.md for RPC endpoints and https://faucet.circle.com for testnet tokens.
> Always check Contract Addresses: https://docs.arc.io/arc/references/contract-addresses.md
> Building beyond Arc? Circle offers skills for the full platform: use-usdc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-usdc/SKILL.md), use-circle-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-circle-wallets/SKILL.md), use-developer-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-developer-controlled-wallets/SKILL.md), use-user-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-user-controlled-wallets/SKILL.md), use-modular-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-modular-wallets/SKILL.md), use-gateway (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-gateway/SKILL.md), use-smart-contract-platform (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-smart-contract-platform/SKILL.md). Full Circle developer docs: https://developers.circle.com/llms.txt.

# App Kits supported blockchains and tokens

> Review supported blockchains, tokens, and token aliases available for App Kits

## Supported blockchains

The App Kit SDK supports the following capabilities and wallet adapters for each
supported blockchain.

<Note>
  Swap is available on mainnet only, with the exception of Arc testnet.
</Note>

| Blockchain | Capabilities | Adapters |
| :- | :- | :- |
| Arbitrum | Send, Bridge, Swap, Unified Balance | Viem, Ethers, Circle Wallets |
| Arc | Send, Bridge, Swap, Unified Balance, Onramp, Earn, Borrow | Viem, Ethers, Circle Wallets |
| Avalanche | Send, Bridge, Swap, Unified Balance | Viem, Ethers, Circle Wallets |
| Base | Send, Bridge, Swap, Unified Balance | Viem, Ethers, Circle Wallets |
| Codex | Send, Bridge | Viem, Ethers |
| Cronos | Send, Bridge | Viem, Ethers, Circle Wallets |
| EDGE | Send, Bridge | Viem, Ethers |
| Ethereum | Send, Bridge, Swap, Unified Balance | Viem, Ethers, Circle Wallets |
| HyperEVM | Send, Bridge, Swap, Unified Balance | Viem, Ethers |
| Injective | Send, Bridge | Viem, Ethers |
| Ink | Send, Bridge, Swap | Viem, Ethers |
| Linea | Send, Bridge, Swap | Viem, Ethers |
| Monad | Send, Bridge, Swap | Viem, Ethers |
| Morph | Send, Bridge | Viem, Ethers |
| OP Mainnet | Send, Bridge, Swap, Unified Balance | Viem, Ethers, Circle Wallets |
| Pharos | Send, Bridge | Viem, Ethers |
| Plasma | Send, Bridge | Viem, Ethers, Circle Wallets |
| Plume | Send, Bridge, Swap | Viem, Ethers |
| Polygon PoS | Send, Bridge, Swap, Unified Balance | Viem, Ethers, Circle Wallets |
| Sei | Send, Bridge, Swap, Unified Balance | Viem, Ethers |
| Solana | Send, Bridge, Swap, Unified Balance | Solana, Circle Wallets |
| Sonic | Send, Bridge, Swap, Unified Balance | Viem, Ethers |
| Unichain | Send, Bridge, Swap, Unified Balance | Viem, Ethers, Circle Wallets |
| World Chain | Send, Bridge, Swap, Unified Balance | Viem, Ethers |
| X Layer | Send, Bridge | Viem, Ethers |
| XDC | Send, Bridge, Swap | Viem, Ethers |

### Blockchain identifiers

For most blockchains, the identifier is the blockchain name with any spaces
replaced by underscores (for example, Arc Testnet → `Arc_Testnet`). Identifiers
are case-sensitive and match the per-capability enums (`BridgeChain`,
`SwapChain`, `UnifiedBalanceChain`, `EarnChain`, `BorrowChain`) exported from
`@circle-fin/app-kit`:

```ts theme={null}
import { BridgeChain } from "@circle-fin/app-kit";

const chain = BridgeChain.Arc_Testnet; // or "Arc_Testnet"
```

Some blockchains have identifier deviations:

| Blockchain | Identifier |
| :- | :- |
| EDGE | `Edge` |
| EDGE Testnet | `Edge_Testnet` |
| OP Mainnet | `Optimism` |
| OP Sepolia | `Optimism_Sepolia` |
| Pharos Atlantic | `Pharos_Testnet` |
| Polygon PoS | `Polygon` |
| Polygon PoS Amoy | `Polygon_Amoy_Testnet` |

### Discover supported blockchains programmatically

The App Kit SDK provides a way to fetch supported blockchain data in code. This
is useful for building a blockchain picker, validating user input against
supported blockchains, or looking up metadata like explorer URLs and testnet
flags.

Each method returns `ChainDefinition[]` with fields like `name`, `isTestnet`,
`explorerUrl`, and protocol config. See
[`getSupportedChains`](/app-kit/references/sdk-reference#getsupportedchains-operationtype)
for the method signature and
[`BaseChainDefinition`](/app-kit/references/sdk-reference#basechaindefinition)
for the full field list.

<Tabs>
  <Tab title="App Kit SDK">
    Pass an optional `operationType` to narrow by capability:

    ```ts theme={null}
    import { AppKit, BorrowChain } from "@circle-fin/app-kit";

    const kit = new AppKit();

    const allChains = kit.getSupportedChains();
    const bridgeChains = kit.getSupportedChains("bridge");
    const swapChains = kit.getSupportedChains("swap");
    const unifiedBalanceChains = kit.getSupportedChains("unifiedBalance");
    const earnChains = kit.getSupportedChains("earn");

    // Borrow uses the BorrowChain enum
    const borrowChains = Object.values(BorrowChain);
    ```

    The top-level App Kit SDK accepts only `operationType`. Bridge filters are
    available on the standalone Bridge Kit. Unified Balance forwarder filters are
    available on the namespaced API:

    ```ts theme={null}
    kit.unifiedBalance.getSupportedChains({
      forwarderSupported: "destination",
    });
    ```
  </Tab>

  <Tab title="Standalone Kits">
    If you import a kit package directly, call `getSupportedChains()` on that kit.
    Each package accepts different optional filters:

    * **Bridge Kit**: `chainType`, `isTestnet`, `forwarderSupported`
    * **Swap Kit, Earn Kit**: none, filter the returned array yourself
    * **Unified Balance Kit**: `forwarderSupported` as `"source"` or `"destination"`

    Onramp Kit and Borrow Kit do not expose `getSupportedChains()`. For Borrow, use
    the `BorrowChain` enum instead.

    <Tabs>
      <Tab title="Bridge Kit">
        ```ts theme={null}
        import { BridgeKit } from "@circle-fin/bridge-kit";

        const kit = new BridgeKit();

        const chains = kit.getSupportedChains({
          chainType: "evm",
          isTestnet: false,
          forwarderSupported: true,
        });
        ```
      </Tab>

      <Tab title="Swap Kit">
        ```ts theme={null}
        import { SwapKit } from "@circle-fin/swap-kit";

        const kit = new SwapKit();

        const chains = kit.getSupportedChains().filter((c) => !c.isTestnet);
        ```
      </Tab>

      <Tab title="Unified Balance Kit">
        ```ts theme={null}
        import { UnifiedBalanceKit } from "@circle-fin/unified-balance-kit";

        const kit = new UnifiedBalanceKit();

        const chains = kit.getSupportedChains({ forwarderSupported: "destination" });
        ```
      </Tab>

      <Tab title="Earn Kit">
        ```typescript theme={null}
        import { EarnKit } from "@circle-fin/earn-kit";

        const kit = new EarnKit();

        const chains = kit.getSupportedChains().filter((c) => !c.isTestnet);
        ```
      </Tab>

      <Tab title="Borrow Kit">
        ```typescript theme={null}
        import { BorrowChain } from "@circle-fin/borrow-kit";

        const chains = Object.values(BorrowChain);
        ```
      </Tab>
    </Tabs>
  </Tab>
</Tabs>

## Supported tokens

<Tip>
  You can specify either a contract address or an [alias](#token-aliases) for any
  supported token.
</Tip>

Each capability supports different tokens:

* **[Send](/app-kit/send)**: Any token. Use [token aliases](#token-aliases) for
  common tokens or the token's contract address for other tokens.
* **[Bridge](/app-kit/bridge)**: USDC, EURC, WETH, cirBTC, and third-party
  assets registered with
  [CCTPx](https://developers.circle.com/cctp/expanded-assets).
* **[Swap](/app-kit/swap)**:
  * Any tokens with enough liquidity to trade with major stablecoins such as
    USDC, EURC, USDT, USDe, DAI, and PYUSD.
  * Native tokens on blockchains where Swap is supported.
  * On Arc, USDC, EURC, and cirBTC.
* **[Unified Balance](/app-kit/unified-balance)**: USDC only.
* **[Onramp](/app-kit/onramp)**: USDC and EURC.
* **[Earn](/app-kit/earn)**: USDC and EURC.
* **[Borrow](/app-kit/borrow)**: cirBTC as collateral.

### Token aliases

App Kits works with any supported token when you supply the contract address.
For convenience, you can also pass any of these case-insensitive aliases
instead. The App Kit SDK resolves each alias to the token's address on the
target blockchain.

* `USDC`
* `EURC`
* `cirBTC`
* `USDT`
* `USDe`
* `DAI`
* `PYUSD`
* `WETH`
* `WBTC`
* `WSOL`
* `WAVAX`
* `WPOL`
* `POL`
* `PLUME`
* `MON`
* `NATIVE`: Uses the blockchain's native token.