> ## 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: Authenticate an agent wallet

> Log in with your email to create an agent wallet session on all supported blockchains.

Authenticating creates an agent session and provisions agent wallets on all
[supported blockchains](/agent-stack/agent-wallets/supported-blockchains)
automatically. You only need to do this once per environment. Sessions last 28
days. Session secrets are stored in your operating system's secure keychain. Run
`circle wallet logout` to clear the session.

This is a prerequisite for all other wallet operations, including
[Fund wallet](/agent-stack/agent-wallets/wallet-operations/fund),
[Transfer USDC](/agent-stack/agent-wallets/wallet-operations/transfer),
[Bridge USDC](/agent-stack/agent-wallets/wallet-operations/bridge), and
[Pay for service](/agent-stack/agent-nanopayments/operations/pay-for-service).

<Warning>
  Never give an AI agent unrestricted access to your email account. Circle sends
  a one-time password (OTP) to the email you log in with. Anyone who can read
  that inbox can use the OTP code to log in to your agent wallet. They can then
  perform any wallet operation, including changing your spending policies. Enter
  the OTP code yourself instead of giving your agent access to your email.
</Warning>

## Prerequisites

Before you begin, ensure you have:

* Installed [Node.js v20.18.2 or later](https://nodejs.org/).
* Installed Circle CLI:

  ```bash theme={null}
  npm install -g @circle-fin/cli
  ```

## Steps

Choose the flow that matches your environment. Use **Interactive** when you can
respond to prompts in a terminal. Use **Non-interactive** for scripts and AI
agents that can't respond to interactive prompts.

<Tabs>
  <Tab title="Interactive">
    <Steps>
      <Step title="Run the login command">
        Run `circle wallet login` with your email address:

        ```bash theme={null}
        circle wallet login you@example.com
        ```

        <Note>
          To use testnet, add `--testnet` to the command. Sessions are stored separately
          for mainnet and testnet and expire after 28 days.
        </Note>

        On first run, Circle CLI prompts you to accept the Terms of Use and
        Privacy Policy.
      </Step>

      <Step title="Enter the one-time password">
        Check your email for the one-time password from Circle. Enter it in
        the terminal to verify your identity. You should see output similar
        to:

        ```text theme={null}
        Logged in as you@example.com
        ```

        Agent wallets are created automatically on all
        [supported blockchains](/agent-stack/agent-wallets/supported-blockchains).
      </Step>

      <Step title="Get your wallet address">
        List your wallets to find the address for the blockchain you want to
        use:

        ```bash theme={null}
        circle wallet list --type agent --chain ARC
        ```

        Copy the address returned. You'll need it for
        [funding your wallet](/agent-stack/agent-wallets/wallet-operations/fund),
        [transferring USDC](/agent-stack/agent-wallets/wallet-operations/transfer),
        [depositing for nanopayments](/agent-stack/agent-nanopayments/operations/deposit),
        and other operations.
      </Step>
    </Steps>
  </Tab>

  <Tab title="Non-interactive (scripts and AI agents)">
    <Steps>
      <Step title="Initialize the login">
        Run `circle wallet login` with `--init` to send the OTP and capture a
        request ID. The `CIRCLE_ACCEPT_TERMS=1` prefix accepts the Circle CLI
        Terms of Use and Privacy Policy so the command doesn't pause for
        input on first run:

        ```bash theme={null}
        CIRCLE_ACCEPT_TERMS=1 circle wallet login you@example.com --init
        ```

        The CLI prints a request ID. Request IDs expire after 10 minutes and
        are consumed on first use.
      </Step>

      <Step title="Complete the login">
        Pass the request ID and the OTP from your inbox:

        ```bash theme={null}
        circle wallet login --request <request-id> --otp B1X-123456
        ```

        OTP codes are alphanumeric. Once login completes, agent wallets are
        created automatically on all
        [supported blockchains](/agent-stack/agent-wallets/supported-blockchains).
      </Step>

      <Step title="Get your wallet address">
        List your wallets to find the address for the blockchain you want to
        use:

        ```bash theme={null}
        circle wallet list --type agent --chain ARC
        ```

        Copy the address returned. You'll need it for
        [funding your wallet](/agent-stack/agent-wallets/wallet-operations/fund),
        [transferring USDC](/agent-stack/agent-wallets/wallet-operations/transfer),
        [depositing for nanopayments](/agent-stack/agent-nanopayments/operations/deposit),
        and other operations.
      </Step>
    </Steps>
  </Tab>
</Tabs>

See the [CLI command reference](/agent-stack/circle-cli/command-reference) for
full syntax and options.