> ## 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. # Update wire routing preferences > Creates or updates the settlement bank routing preferences for a wire fiat account. At least one of `inboundBankLabel` or `outboundBankLabel` must be provided in the request. Note: This endpoint will reject updates if the account has active Express routes configured. Accounts with Express routes must update preferences through the Circle Mint UI. ## OpenAPI ````yaml openapi/account.yaml put /v1/businessAccount/banks/wires/{fiatAccountId}/routingPreferences openapi: 3.0.2 info: version: ${version} title: Core Functionality description: > All of Circle's APIs share a common set of core functionality that lets you manage your Circle Account in a programmatic way. With a Circle Account your business can deposit traditional money from 80+ countries and seamlessly convert them into "digital currency dollars": USDC. You can then use USDC for everyday payments and treasury flows. servers: - url: https://api-sandbox.circle.com - url: https://api.circle.com security: [] tags: - name: Balances description: Get information on settled and unsettled balances. - name: Payouts description: Create and get information on 1st party payouts. - name: Wires description: >- Create, get instructions, and get information on 1st party bank accounts for wire transfers. - name: CUBIX description: Create and get information on CUBIX accounts. - name: PIX description: Create and get information on PIX accounts. - name: Transfers description: Create and get information on 1st party transfers. - name: Addresses description: Generate and get information on blockchain addresses. - name: Deposits description: Get information on 1st party deposits. - name: Payments description: Create, cancel, refund, and get updates on card payments. - name: Settlement Bank Routing description: View and manage settlement bank routing preferences for fiat accounts. - name: Reporting description: >- Retrieve transaction and balance reports, including ISO 20022 (CAMT.053) statements and managed-payment reports. paths: /v1/businessAccount/banks/wires/{fiatAccountId}/routingPreferences: put: tags: - Settlement Bank Routing summary: Update wire routing preferences description: > Creates or updates the settlement bank routing preferences for a wire fiat account. At least one of `inboundBankLabel` or `outboundBankLabel` must be provided in the request. Note: This endpoint will reject updates if the account has active Express routes configured. Accounts with Express routes must update preferences through the Circle Mint UI. operationId: updateWireRoutingPreferences parameters: - $ref: '#/components/parameters/FiatAccountIdPath' requestBody: content: application/json: schema: $ref: '#/components/schemas/RoutingPreferencesRequest' responses: '200': description: Successfully updated routing preferences for the wire account. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: title: UpdateWireRoutingPreferencesResponse properties: data: $ref: '#/components/schemas/RoutingPreferencesResponse' examples: response: value: data: currency: USD inbound: bankLabel: customers_bank bankName: Customers Bank createDate: '2020-04-10T02:13:30.000Z' updateDate: '2020-04-10T02:13:30.000Z' outbound: bankLabel: customers_bank bankName: Customers Bank createDate: '2020-04-10T02:13:30.000Z' updateDate: '2020-04-10T02:13:30.000Z' '400': $ref: '#/components/responses/BadRequestSettlementRoutingPreferences' '401': $ref: '#/components/responses/NotAuthorized' '404': $ref: '#/components/responses/NotFoundFiatAccount' security: - bearerAuth: [] components: parameters: FiatAccountIdPath: name: fiatAccountId description: Universally unique identifier (UUID v4) of a fiat account. in: path required: true schema: type: string format: uuid example: b3d9d2d5-4c12-4946-a09d-953e82fae2b0 schemas: RoutingPreferencesRequest: type: object description: >- Request body for updating routing preferences. At least one of inboundBankLabel or outboundBankLabel must be provided. required: - currency properties: currency: type: string description: >- The currency code (e.g., USD, BRL). Must match a supported currency for the account type. example: USD inboundBankLabel: type: string description: Bank identifier for inbound (deposit) transactions. example: customers_bank outboundBankLabel: type: string description: Bank identifier for outbound (withdrawal) transactions. example: scb RoutingPreferencesResponse: type: object description: The current routing preferences for a fiat account. required: - currency properties: currency: type: string description: The currency code. example: USD inbound: description: The inbound routing preference (null if not set). nullable: true allOf: - $ref: '#/components/schemas/RoutingPreference' outbound: description: The outbound routing preference (null if not set). nullable: true allOf: - $ref: '#/components/schemas/RoutingPreference' RoutingPreference: type: object description: A routing preference for a specific direction (inbound or outbound). required: - bankLabel - bankName - createDate - updateDate properties: bankLabel: type: string description: Unique identifier for the bank. example: customers_bank bankName: type: string description: Human-readable bank name. example: Customers Bank createDate: $ref: '#/components/schemas/UtcTimestamp' updateDate: $ref: '#/components/schemas/UtcTimestamp' Error: type: object required: - code - message properties: code: type: integer example: 400 message: type: string example: Something went wrong. UtcTimestamp: type: string description: ISO-8601 UTC date/time format. example: '2020-04-10T02:13:30.000Z' headers: XRequestId: description: >- Universally unique identifier (UUID v4) for the request. Helpful for identifying a request when communicating with Circle support. schema: type: string format: uuid example: 2adba88e-9d63-44bc-b975-9b6ae3440dde responses: BadRequestSettlementRoutingPreferences: 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' examples: '1173': value: code: 1173 message: Institution is not eligible for routing '1174': value: code: 1174 message: >- At least one of inbound or outbound institution must be provided '1175': value: code: 1175 message: >- Cannot update routing preferences for accounts with Express routes via the API. Please use the Circle Mint UI 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: type: object title: NotAuthorized required: - code - message properties: code: type: integer example: 400 message: type: string example: Something went wrong. example: code: 401 message: Malformed authorization. examples: response: value: code: 401 message: Malformed authorization. NotFoundFiatAccount: description: Fiat account not found or does not belong to the authenticated entity. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: $ref: '#/components/schemas/Error' examples: '1112': value: code: 1112 message: Fiat account not found securitySchemes: bearerAuth: type: http scheme: bearer ````