> ## 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.

# Paymaster

> Pay gas fees with USDC

Circle has a network of permissionless token paymasters that enables end-users
to pay for network (gas) fees using USDC tokens, instead of chain native tokens.

Paying for gas in USDC has the following advantages:

* USDC holders don't need to source native tokens to transact in USDC.
* End-users pay for network fees in a familiar unit, making network pricing
  easier to understand.

The Circle Paymaster supports the ERC-4337 standard and thus supports any wallet
adhering to that standard. This documentation provides information on how to
integrate with the permissionless Circle Paymaster so that your users can pay
for gas fees in USDC.

There is a 10% surcharge on gas fees to account for operational costs. The 10%
surcharge only applies to Arbitrum and Base (and their testnets). The Paymaster
only supports USDC tokens.

Circle Paymaster supports the
[ERC-4337 v0.7](https://github.com/eth-infinitism/account-abstraction/releases/tag/v0.7.0)
and
[ERC-4337 v0.8](https://github.com/eth-infinitism/account-abstraction/releases/tag/v0.8.0)
on multiple chains. For more information, see
[Supported chains](#supported-chains) below.

In the following pages, `Paymaster v0.7` denotes the Paymaster that supports
Entrypoint v0.7 and `Paymaster v0.8` denotes the Paymaster that supports
Entrypoint v0.8.

## Key features

The Circle Paymaster provides many enhancements for new crypto users who may not
be familiar with gas fees or native tokens. Paymasters allow you to build and
integrate wallets that don't require native tokens for gas, allowing you to
provide users with an experience similar to traditional finance.

### Reliable execution

Circle ensures that there is always a sufficient amount of native gas token for
each supported chain, managing swaps and balances behind-the-scenes to ensure a
reliable, consistent experience with the Paymaster smart contracts.

### Permissionless usage

The Paymaster is an onchain smart contract that any developer can integrate. You
don't need to sign up for a Circle Developer account or generate any API keys.
The Paymaster has no dependency on offchain APIs, and you can extend it for your
specific use case.

### Onboarding without native tokens

Using the USDC smart contract, you can set up an ERC-20 approval with the
Paymaster without using any native tokens. You can then pay for a smart contract
account deployment using USDC set to the pre-deployed account address with a
signed permit. This means that you can transact without ever needing to hold the
blockchain native token.

## Supported chains

| EntryPoint | Chains |
| - | - |
| [ERC-4337 v0.7](https://github.com/eth-infinitism/account-abstraction/releases/tag/v0.7.0) | Arbitrum and Base |
| [ERC-4337 v0.8](https://github.com/eth-infinitism/account-abstraction/releases/tag/v0.8.0) | Arbitrum, Avalanche, Base, Ethereum, Optimism, Polygon and Unichain |

## Related products

Circle Paymaster allows users to pay gas fees in USDC. If you want to sponsor
network fees for your users, see [Gas Station](/wallets/gas-station).

### Comparison with Gas Station

| Category | Circle Paymaster | Gas Station |
| - | - | - |
| **Description** | A permissionless smart contract that allows users to pay gas fees in USDC instead of native tokens. | A feature of Wallets that allows developers to sponsor gas fees for their users. |
| **Circle account** | Not required | Required |
| **Compatible wallets** | Any ERC-4337-compliant wallet | Circle Wallets |
| **Gas fees paid in** | USDC | Fiat currency via credit card |
| **Pricing model** | 10% of the gas fee | 5% of the gas fee |
| **Paid by** | End user | Developer |