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

> ## Agent Instructions
> Before reading these docs, install the relevant Circle Skill to get pre-loaded context — skills are LLM-optimized and cover architecture decisions, correct flows, and common pitfalls. 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. Available skills: use-usdc https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-usdc/SKILL.md (balances, transfers, approvals on EVM and Solana); EURC has no skill — see https://developers.circle.com/stablecoins/what-is-eurc.md; bridge-stablecoin https://github.com/circlefin/skills/blob/master/plugins/circle/skills/bridge-stablecoin/SKILL.md (crosschain transfers via CCTP, USDC, EURC, and third-party assets); use-arc https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-arc/SKILL.md (Arc chain config, contract deployment, USDC bridging — Arc docs: https://docs.arc.io/llms.txt); use-circle-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-circle-wallets/SKILL.md (choose wallet type); use-developer-controlled-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-developer-controlled-wallets/SKILL.md (custodial wallets for payouts and treasury); use-user-controlled-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-user-controlled-wallets/SKILL.md (embedded wallets with Web2 login); use-modular-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-modular-wallets/SKILL.md (smart contract wallets with passkeys and ERC-4337); use-gateway https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-gateway/SKILL.md (unified USDC balance, nanopayments); use-smart-contract-platform https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-smart-contract-platform/SKILL.md (deploy, interact, monitor contracts). Pair any skill with the Circle MCP server for live SDK signatures, contract addresses, and chain IDs: {"mcpServers":{"circle":{"url":"https://api.circle.com/v1/codegen/mcp"}}}.
> Read the product overview first. Each product has an overview explaining when and why to use it. Read it before quickstarts.
> Pick the right wallet type. Developer-controlled (you hold keys), user-controlled (end user holds keys via PIN/social login), or modular (smart contract wallets with passkeys). See https://developers.circle.com/wallets.md.
> Use CCTP V2 for crosschain transfers. CCTP natively transfers USDC and EURC via burn-and-mint, and supports permissionless wrapping of third-party assets via lock-and-mint. V1 is legacy; always use V2 unless V1 is specified or the chain requires it (Noble, Sui, and Aptos still require V1). Migration guide: https://developers.circle.com/cctp/migration-from-v1-to-v2.md.
> Use Bridge Kit for frontend bridging. Wraps CCTP with a simpler SDK for user-facing apps. Use CCTP directly for backend transfers.
> Gas Station vs Paymaster. Gas Station sponsors gas for Circle Wallet transactions. Paymaster lets users pay gas in USDC. Different use cases — read both overviews.
> Gateway Nanopayments for sub-cent payments. Gasless USDC micropayments down to $0.000001 via x402 and batched settlement. For pay-per-request APIs, AI agent payments, streaming.
> Look up USDC addresses per chain. Never hardcode — use https://developers.circle.com/stablecoins/usdc-contract-addresses.md.
> Prefer SDKs over raw API calls. Node.js and Python SDKs handle auth, retries, and errors.
> API key required. Bearer token in Authorization header. Testnet and mainnet use separate keys and may use different base URLs depending on the product.
> Set up webhooks when available. Most operations are async. Webhooks deliver transaction confirmations and state changes.
> When calling list endpoints, paginate using pageSize and pageAfter until no nextPageAfter cursor is returned—stopping at the first page silently misses records.
> Building an AI agent? Start with the Agent Stack—Circle CLI, agent wallets, and nanopayments built for autonomous use cases: https://developers.circle.com/agent-stack.md.

# How-to: Configure rate limits and transfer caps

> Set the rate limit, max transfer amount, and rate-limit window on a CCTP for non-USDC TokenManager.

The `TokenManager` applies two transfer controls per token: a rate limit over a
fixed epoch window, and a per-transaction maximum transfer amount. The rate
limit tracks inbound and outbound flow; the max transfer amount applies to
outbound transfers. Both controls live on the `TokenManager` for the token. Use
this guide to configure them.

Attestation does not bypass destination `TokenManager` checks. An inbound
transfer can still be rejected by the rate limit or blocked while the token is
paused.

> [!WARNING]
>
> Custom token issuers must configure rate limits and a max transfer amount before
> allowing public transfers. A rate limit configured as `0` blocks inbound and
> outbound flows. Every `crossChainTransfer` call reverts until you set a non-zero
> limit.

## How the throttles behave

* **Rate limit**: Caps the absolute net flow (`|flowIn - flowOut|`) within each
  fixed epoch window. It applies to inbound and outbound flow. The default
  window length is six hours. Setting the rate limit to `0` blocks both
  directions. After configuration, always verify the limit is non-zero before
  your first `crossChainTransfer`; a common mistake is configuring with
  `rateLimit: 0` and skipping this guide.
* **Max transfer amount**: Caps the size of a single outbound transfer
  transaction. Applies on top of the rate limit to prevent oversize single
  transfers regardless of the headroom remaining in the rate-limit window.
  Setting `maxTransferAmount` to `0` blocks all outbound transfers. Use
  `type(uint256).max` (or `2n ** 256n - 1n` in TypeScript) to disable the
  per-transfer cap.

For example, with a rate limit of `1,000,000` over six hours:

* A user transfers `300,000` out and `100,000` in during the window. Net
  outbound consumed is `200,000`. Remaining headroom: `800,000`.
* A second user attempts to transfer `900,000` out in the same window. The
  transfer reverts because net outbound would exceed `1,000,000`.

## Prerequisites

Before you begin, ensure that you've:

* Obtained the `tokenId` for the token you want to configure.
* Confirmed the wallet you'll use holds the operator role for that token's
  `TokenManager`.

## Steps

The snippets assume that `publicClient`, `walletClient`, `serviceAddress`, and
`tokenId` are already initialized. Each code example includes only the ABI
entries needed for that operation.

Receipt-handling code is omitted for brevity, but you should wait for each
state-changing transaction to confirm before reading the updated state or
submitting the next transaction.

**1. Discover the TokenManager address**

Read the local `TokenManager` address from the `CrossChainTokenService`:

```typescript TypeScript theme={null}
const serviceAbi = [
  {
    name: "resolveTokenManager",
    type: "function",
    stateMutability: "view",
    inputs: [{ name: "tokenId", type: "bytes32" }],
    outputs: [{ name: "tokenManager", type: "address" }],
  },
] as const;

const tokenManager: `0x${string}` = await publicClient.readContract({
  address: serviceAddress,
  abi: serviceAbi,
  functionName: "resolveTokenManager",
  args: [tokenId],
});
```

**2. Set the rate limit**

Call `setRateLimit` with the maximum absolute net flow (`|flowIn - flowOut|`)
per window in the token's smallest unit.

```typescript TypeScript theme={null}
const rateLimitAbi = [
  {
    name: "setRateLimit",
    type: "function",
    stateMutability: "nonpayable",
    inputs: [{ name: "rateLimit", type: "uint256" }],
    outputs: [],
  },
] as const;

await walletClient.writeContract({
  address: tokenManager,
  abi: rateLimitAbi,
  functionName: "setRateLimit",
  args: [5_000_000n * 10n ** 18n],
});
```

**3. Set the max transfer amount**

Call `setMaxTransferAmount` to cap the size of a single outbound transfer.

```typescript TypeScript theme={null}
const maxTransferAmountAbi = [
  {
    name: "setMaxTransferAmount",
    type: "function",
    stateMutability: "nonpayable",
    inputs: [{ name: "maxTransferAmount", type: "uint256" }],
    outputs: [],
  },
] as const;

await walletClient.writeContract({
  address: tokenManager,
  abi: maxTransferAmountAbi,
  functionName: "setMaxTransferAmount",
  args: [500_000n * 10n ** 18n],
});
```

**4. Set the rate-limit window (optional)**

The default window is six hours. To change it, call `setRateLimitWindow` with
the new window length in seconds.

```typescript TypeScript theme={null}
const rateLimitWindowAbi = [
  {
    name: "setRateLimitWindow",
    type: "function",
    stateMutability: "nonpayable",
    inputs: [{ name: "window", type: "uint256" }],
    outputs: [],
  },
] as const;

await walletClient.writeContract({
  address: tokenManager,
  abi: rateLimitWindowAbi,
  functionName: "setRateLimitWindow",
  args: [3600n], // 1 hour
});
```

**5. Verify the configuration**

Read the current values from the `TokenManager` and compare them with the values
you selected for the preceding configuration steps. If you skipped the optional
window step, compare `rateLimitWindow` with the six-hour default. If `rateLimit`
is still `0`, transfers revert until you call `setRateLimit` with a non-zero
amount (in the token's smallest unit).

```typescript TypeScript theme={null}
const tokenManagerReadAbi = [
  {
    name: "rateLimit",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ name: "", type: "uint256" }],
  },
  {
    name: "maxTransferAmount",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ name: "", type: "uint256" }],
  },
  {
    name: "rateLimitWindow",
    type: "function",
    stateMutability: "view",
    inputs: [],
    outputs: [{ name: "", type: "uint256" }],
  },
] as const;

const [rateLimit, maxTransferAmount, rateLimitWindow] = await Promise.all([
  publicClient.readContract({
    address: tokenManager,
    abi: tokenManagerReadAbi,
    functionName: "rateLimit",
  }),
  publicClient.readContract({
    address: tokenManager,
    abi: tokenManagerReadAbi,
    functionName: "maxTransferAmount",
  }),
  publicClient.readContract({
    address: tokenManager,
    abi: tokenManagerReadAbi,
    functionName: "rateLimitWindow",
  }),
]);

console.log({ rateLimit, maxTransferAmount, rateLimitWindow });
if (rateLimit === 0n) {
  throw new Error("rateLimit is 0: token flows are blocked");
}
```