> ## 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. # Create an ACH bank account > Create a bank account for ACH transfers. ## OpenAPI ````yaml openapi/accounts.yaml post /v1/banks/ach openapi: 3.1.0 info: version: 1.0.0 title: Accounts (Stablecoin) API description: > Circle's Accounts API provides endpoints for managing stablecoin accounts -- including transfers, withdrawals, deposits, wire and ACH bank accounts, and blockchain addresses. An **Account** is a general representation of a ledger or custody object that holds balances. It can be a business account, a stablecoin account ledger for an end user, an extra sub-ledger, or any future custody solution. license: name: Circle License url: https://circle.com/terms servers: - url: https://api-sandbox.circle.com - url: https://api.circle.com security: [] tags: - name: Accounts description: Manage accounts. - name: Account Groups description: Manage custody account groups and their memberships. - name: Limits description: View effective account limits and current usage. - name: Transfers description: > Move funds between accounts or out to a verified blockchain address, and track inbound and outbound onchain transfers. - name: Transactions description: | Get a unified, customer-friendly view of account transaction activity. - name: Wires description: Manage account bank accounts for wire transfers. - name: Deposits description: Get information on account bank deposits. - name: Withdrawals description: Manage account bank withdrawals (fiat offramp). - name: ACH description: Manage account bank accounts for ACH transfers. - name: Deposit Addresses description: Manage account deposit addresses. - name: Recipient Addresses description: Manage account recipient addresses used for transfers. - name: Passkeys description: > Manage WebAuthn passkeys and Strong Customer Authentication (SCA) challenges for end users. - name: Crypto Payments description: > Get crypto payments and crypto refunds received through payment intents. Available for Digital Asset Accounts only on custody accounts (`purpose: custody`), and only for third-party payments. Not supported when the distributor or the end user is under the Circle FR (`CIRCLE_FR`) or Circle SG (`CIRCLE_SG`) legal entity. - name: Crypto Payment Intents description: > Create, expire, refund, and track payment intents for receiving crypto payments. Available for Digital Asset Accounts only on custody accounts (`purpose: custody`), and only for third-party payments. Not supported when the distributor or the end user is under the Circle FR (`CIRCLE_FR`) or Circle SG (`CIRCLE_SG`) legal entity. - name: Crypto Payouts description: > Create and track crypto payouts to recipient addresses. Available for Digital Asset Accounts only on custody accounts (`purpose: custody`), and only for third-party payouts. Not supported when the distributor or the end user is under the Circle FR (`CIRCLE_FR`) or Circle SG (`CIRCLE_SG`) legal entity. - name: Crypto Address Book description: > Manage address book recipients used as crypto payout destinations. Available for Digital Asset Accounts only on custody accounts (`purpose: custody`), and only for third-party payouts. Not supported when the distributor or the end user is under the Circle FR (`CIRCLE_FR`) or Circle SG (`CIRCLE_SG`) legal entity. - name: FX Trades description: | Quote and execute USDC <> EURC swaps for end users' accounts. - name: FX Settlements description: Get settlements of FX trades. - name: Webhook Subscriptions description: Manage subscriptions to Digital Asset Accounts webhook notifications. - name: Webhooks description: | Webhook event payloads Circle sends to a subscribed endpoint. paths: /v1/banks/ach: post: tags: - ACH summary: Create an ACH bank account description: Create a bank account for ACH transfers. operationId: createACHAccount requestBody: content: application/json: schema: $ref: '#/components/schemas/ACHCreationRequest' responses: '201': description: Successfully created a bank account for ACH transfers. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: $ref: '#/components/schemas/CreateACHAccountResponse' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/NotAuthorized' '404': $ref: '#/components/responses/NotFound' '500': $ref: '#/components/responses/InternalServerError' security: - bearerAuth: [] components: schemas: ACHCreationRequest: description: Request object used to create a bank account for ACH transfers. type: object required: - idempotencyKey - accountNumber - routingNumber - accountType - billingDetails - riskSignals properties: idempotencyKey: $ref: '#/components/schemas/IdempotencyKey' clientEntityId: description: Identifier of the client entity. Required for 3rd-party flows. type: string format: uuid example: a3f1b2c4-d5e6-7890-abcd-ef1234567890 accountNumber: description: Account number that identifies the bank account. type: string maxLength: 30 example: '424233434333' routingNumber: description: ABA routing number for the bank account. type: string minLength: 9 maxLength: 9 example: '121000248' accountType: $ref: '#/components/schemas/ACHAccountType' billingDetails: $ref: '#/components/schemas/ACHBillingDetailsRequest' riskSignals: $ref: '#/components/schemas/RiskSignals' CreateACHAccountResponse: title: CreateACHAccountResponse properties: data: $ref: '#/components/schemas/ACH' example: data: id: 4771bc24-fcb7-4046-a94d-39feec11a4a0 status: pending routingNumber: '121000248' description: WELLS FARGO BANK, NA ****4333 accountType: checking billingDetails: name: Joe Bloggs line1: Address1 line2: Address2 city: City postalCode: '123' district: CA country: US fingerprint: 8c2afcd1-640f-4160-a303-659e1919b8e5 createDate: '2026-06-08T21:56:49.310Z' updateDate: '2026-06-08T21:56:49.310Z' IdempotencyKey: type: string description: >- Universally unique identifier (UUID v4) idempotency key. This key is utilized to ensure exactly-once execution of mutating requests. format: uuid example: ba943ff1-ca16-49b2-ba55-1057e70ca5c7 ACHAccountType: description: Type of the bank account. type: string enum: - checking - savings example: checking ACHBillingDetailsRequest: type: object required: - name properties: name: type: string description: Full name of the bank account holder. maxLength: 1024 minLength: 3 pattern: ^[\x20-\x7E]{3,1024}$ example: Joe Bloggs line1: type: string description: Line one of the street address. maxLength: 1024 example: Address1 line2: type: string description: Line two of the street address. maxLength: 1024 example: Address2 city: type: string description: City portion of the address. maxLength: 1024 example: City postalCode: type: string description: Postal / ZIP code of the address. maxLength: 16 example: '123' district: type: string description: State / County / Province / Region portion of the address. example: CA country: type: string description: Country portion of the address. ISO 3166-1 alpha-2. example: US email: type: string description: Email address of the bank account holder. maxLength: 1024 example: joe.bloggs@example.com phone: type: string description: Phone number of the bank account holder in E.164 format. pattern: ^\+?[1-9]\d{1,14}$ example: '+14155550100' RiskSignals: type: object description: > Risk metadata for the end user initiating the request. All three fields must be present. `deviceId` must be the identifier returned by `checkDevice()` in the `@circle-fin/device-checks` SDK. Circle resolves it against the device check that produced it, so an identifier you generate yourself does not resolve. When it does not resolve, the request is accepted and then declined: the endpoint returns `201`, and the transaction later settles as `failed` with `errorCode` `transfer_denied`. See [Collect device risk signals](https://developers.circle.com/end-user-onboarding/howtos/collect-device-risk-signals). required: - ipAddress - sessionId - deviceId properties: ipAddress: type: string description: IP address of the end user initiating the request. example: 203.0.113.42 sessionId: type: string description: Identifier for the end user's session. example: 8f3b2c1a-9d4e-4f6a-b7c8-1e2d3f4a5b6c deviceId: type: string description: > The identifier returned by `checkDevice()` in the `@circle-fin/device-checks` SDK. Store that value and send it here. Do not generate your own device identifier: Circle looks this value up against the completed device check, and an unrecognized value causes the transaction to be declined after the endpoint has already returned `201`. example: 2a7d9e5f-1c3b-4a8e-9f0d-6b5c4a3e2d1f XRequestId: type: string format: uuid example: 2adba88e-9d63-44bc-b975-9b6ae3440dde ACH: type: object description: An ACH bank account. required: - id - status - routingNumber - description - accountType - billingDetails - fingerprint - createDate - updateDate properties: id: $ref: '#/components/schemas/Id' type: type: string example: ach status: $ref: '#/components/schemas/ExternalFiatAccountStatus' routingNumber: description: ABA routing number for the bank account. type: string example: '121000248' description: type: string description: Bank name plus last four digits of the bank account number. example: WELLS FARGO BANK, NA ****4333 accountType: $ref: '#/components/schemas/ACHAccountType' billingDetails: $ref: '#/components/schemas/BillingDetails' fingerprint: $ref: '#/components/schemas/Fingerprint' riskEvaluation: $ref: '#/components/schemas/RiskEvaluation' createDate: $ref: '#/components/schemas/UtcTimestamp' updateDate: $ref: '#/components/schemas/UtcTimestamp' Error: type: object required: - code - message properties: code: type: integer description: > Circle internal status code from the platform `CoreStatusCode` enum (and its domain-specific extensions). **This is not the HTTP status code** — `-1` is the catch-all unknown error, `1`/`2` indicate API parameter problems, `3` is forbidden, `4` is unauthorized, and larger values identify domain-specific failures. Consumers should rely on the HTTP status line for transport-level error class and on this field for the specific Circle error case. example: 2 message: type: string description: >- Internal error message; suitable for logging but not for end-user display. example: API parameter invalid. externalMessage: type: string description: > End-user-displayable error message. Present when the server has generated a customer-facing variant for this error; omitted otherwise. example: The provided amount exceeds the maximum allowed. errors: type: array description: Additional request-field validation errors, when available. items: $ref: '#/components/schemas/ErrorDetail' Id: type: string description: Unique system-generated identifier for the entity. format: uuid example: b8627ae8-732b-4d25-b947-1df8f4007a29 ExternalFiatAccountStatus: description: Status of the account. type: string enum: - pending - complete - failed BillingDetails: type: object required: - name - city - country - line1 - postalCode properties: name: type: string description: Full name of the card or bank account holder. maxLength: 1024 example: Satoshi Nakamoto city: type: string description: City portion of the address. maxLength: 1024 example: Boston country: type: string description: Country portion of the address. ISO 3166-1 alpha-2. maxLength: 2 example: US line1: type: string description: Line one of the street address. maxLength: 1024 example: 100 Money Street line2: type: string description: Line two of the street address. maxLength: 1024 example: Suite 1 district: description: State / County / Province / Region portion of the address. type: string maxLength: 16 example: MA postalCode: type: string description: Postal / ZIP code of the address. maxLength: 16 example: '01234' Fingerprint: type: string description: A UUID that uniquely identifies the account number. example: eb170539-9e1c-4e92-bf4f-1d09534fdca2 RiskEvaluation: type: - object - 'null' description: >- Results of risk evaluation. Only present if the payment is denied by Circle's risk service. properties: decision: description: Enumerated decision of the account. type: string enum: - approved - denied - review reason: description: Risk reason for the definitive decision outcome. type: - string - 'null' example: '3000' UtcTimestamp: type: string description: ISO-8601 UTC date/time format. example: '2020-04-10T02:13:30.000Z' ErrorDetail: type: object required: - error - message properties: error: type: string description: Machine-readable error identifier. example: invalid_value location: type: string description: Query parameter or request field that caused the error. example: assetType message: type: string description: Human-readable description of the specific error. example: The operation and assetType combination is invalid. headers: XRequestId: description: > Circle-generated universally unique identifier (UUID v4). Useful for identifying a specific request when communicating with Circle Support. schema: $ref: '#/components/schemas/XRequestId' responses: BadRequest: description: The request cannot be processed due to a client error. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: $ref: '#/components/schemas/Error' example: code: 2 message: API parameter invalid. NotAuthorized: description: >- The request has not been applied because it lacks valid authentication credentials. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: $ref: '#/components/schemas/Error' example: code: 4 message: Unauthorized. NotFound: description: The specified resource was not found. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: $ref: '#/components/schemas/Error' example: code: 404 message: Not found. InternalServerError: description: >- The server encountered an unexpected condition that prevented it from fulfilling the request. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: $ref: '#/components/schemas/Error' example: code: -1 message: 'Something went wrong. errId: 1f0b0c455e40f753f07b4f0ae6abd4b4' securitySchemes: bearerAuth: type: http scheme: bearer ````