> ## 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: Transfer funds internally > Move funds instantly between accounts with no blockchain fees Move funds between two accounts in the same program instantly and with no blockchain fees. You can verify balances on both the source and destination accounts before and after the transfer. ## Prerequisites Before you begin: * Obtain an API key for Digital Asset Accounts from Circle. * Have two onboarded and active accounts in the same program, each with an `accountId`. For details on how accounts relate to programs, see [Account structure](/digital-asset-accounts/concepts/account-structure). * Ensure at least one account has a funded balance. * Review whether Strong Customer Authentication (SCA) applies. Circle requires SCA headers on transfers for end users in the European Economic Area (EEA). See [Implement SCA](/digital-asset-accounts/howtos/strong-customer-authentication). * Run a device check for the end user and keep the `deviceId` it returns. Every transfer request carries it in `riskSignals`. See [Collect device risk signals](/end-user-onboarding/howtos/collect-device-risk-signals). * Install cURL on your development machine. The Digital Asset Accounts API base URL is `https://api-sandbox.circle.com` for sandbox and `https://api.circle.com` for production. Set your API key in the `Authorization` header using the format `Bearer YOUR_API_KEY`. See [Sandbox environment](/digital-asset-accounts/references/testing-in-sandbox) and [Going to production](/digital-asset-accounts/references/going-to-production) for environment details. ## Steps ### Step 1. Check source and destination balances Before creating the transfer, verify the balances of both accounts. The source account must have sufficient funds to cover the transfer amount. **Check source balance** ```shell theme={null} curl --request GET \ --url https://api-sandbox.circle.com/v1/accounts/${SOURCE_ACCOUNT_ID} \ --header 'Accept: application/json' \ --header 'Authorization: Bearer ${YOUR_API_KEY}' ``` **Response** ```json theme={null} { "data": { "balances": [ { "amount": "10000.00", "currency": "USD" } ] } } ``` ### Step 2. Create an internal transfer Initiate the transfer by specifying both the source and destination as `account` types with their respective account IDs. Internal transfers complete instantly. ```shell theme={null} curl --request POST \ --url https://api-sandbox.circle.com/v1/accounts/transfers \ --header 'Accept: application/json' \ --header 'Authorization: Bearer ${YOUR_API_KEY}' \ --header 'Content-Type: application/json' \ --data ' { "idempotencyKey": "${RANDOM_UUID}", "source": { "type": "account", "id": "${SOURCE_ACCOUNT_ID}" }, "destination": { "type": "account", "id": "${DEST_ACCOUNT_ID}" }, "amount": { "amount": "2500.00", "currency": "USD" }, "riskSignals": { "ipAddress": "${END_USER_IP}", "sessionId": "${SESSION_ID}", "deviceId": "${DEVICE_ID}" } } ' ``` **Response** ```json theme={null} { "data": { "id": "f1a2b3c4-d5e6-7890-abcd-ef1234567890", "status": "complete", "amount": { "amount": "2500.00", "currency": "USD" }, "source": { "type": "account", "id": "1017381855" }, "destination": { "type": "account", "id": "1000661542" }, "createDate": "2026-03-15T12:00:00Z", "updateDate": "2026-03-15T12:00:00Z" } } ``` Internal account-to-account transfers complete instantly and return a `complete` status in the response. There are no blockchain fees or processing delays. If the source account has insufficient funds, the API returns an error. Verify the balance before creating a transfer. ### Step 3. Verify both balances Confirm that funds have moved correctly by checking the balances of both accounts. **Source balance** ```shell theme={null} curl --request GET \ --url https://api-sandbox.circle.com/v1/accounts/${SOURCE_ACCOUNT_ID} \ --header 'Accept: application/json' \ --header 'Authorization: Bearer ${YOUR_API_KEY}' ``` **Response** ```json theme={null} { "data": { "balances": [ { "amount": "7500.00", "currency": "USD" } ] } } ``` **Destination balance** ```shell theme={null} curl --request GET \ --url https://api-sandbox.circle.com/v1/accounts/${DEST_ACCOUNT_ID} \ --header 'Accept: application/json' \ --header 'Authorization: Bearer ${YOUR_API_KEY}' ``` **Response** ```json theme={null} { "data": { "balances": [ { "amount": "2500.00", "currency": "USD" } ] } } ``` The source account balance decreased by 2,500 USD and the destination account balance increased by the same amount. ## Look up transfers ### Get a transfer by ID Retrieve the details of a specific transfer using the transfer ID returned when you created it. ```shell theme={null} curl --request GET \ --url https://api-sandbox.circle.com/v1/accounts/transfers/${TRANSFER_ID} \ --header 'Accept: application/json' \ --header 'Authorization: Bearer ${YOUR_API_KEY}' ``` **Response** ```json theme={null} { "data": { "id": "f1a2b3c4-d5e6-7890-abcd-ef1234567890", "status": "complete", "amount": { "amount": "2500.00", "currency": "USD" }, "source": { "type": "account", "id": "1017381855" }, "destination": { "type": "account", "id": "1000661542" }, "createDate": "2026-03-15T12:00:00Z", "updateDate": "2026-03-15T12:00:00Z" } } ``` ### List transfers for an account Retrieve all transfers for an account. This endpoint returns both internal and external transfers in reverse order and supports pagination. ```shell theme={null} curl --request GET \ --url 'https://api-sandbox.circle.com/v1/accounts/transfers?accountId=${ACCOUNT_ID}&pageSize=25' \ --header 'Accept: application/json' \ --header 'Authorization: Bearer ${YOUR_API_KEY}' ``` **Response** ```json theme={null} { "data": [ { "id": "f1a2b3c4-d5e6-7890-abcd-ef1234567890", "status": "complete", "amount": { "amount": "2500.00", "currency": "USD" }, "source": { "type": "account", "id": "1017381855" }, "destination": { "type": "account", "id": "1000661542" }, "createDate": "2026-03-15T12:00:00Z", "updateDate": "2026-03-15T12:00:00Z" } ] } ``` ## See also * [Account structure](/digital-asset-accounts/concepts/account-structure) * [Transaction states](/digital-asset-accounts/references/transaction-states) * [Set up webhook notifications](/api-reference/webhook-endpoints#v2-notifications)