> ## 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: Respond to an RFI This guide explains how to respond to an RFI request that is system-initiated. In a system-initiated RFI, you are notified either synchronously when a payment is created, or asynchronously by an RFI webhook. This guide doesn't cover how to respond to an RFI when it is initiated by a support ticket. For RFIs initiated this way, you must follow the support ticket workflow. ## Steps When a system-initiated RFI is created by a BFI, you are notified in one of two ways: 1. In the synchronous response to the payment creation endpoint. When you create a payment, the endpoint responds with the created payment record containing a non-null `activeRfi` field. 2. Asynchronously by an RFI webhook. This can occur at any time in the payment flow after the payment is created. The RFI webhook doesn't contain the entire RFI object. Once you have the full RFI object, you can use the following steps to respond to the RFI. ### Step 1: Get the RFI requirements and certificate Before you respond to an RFI, you need to get the requirements and the certificate used for encrypting RFI responses. The RFI requirements are available in the RFI object. If the RFI was created synchronously, the full object is included in the `activeRfi` field of the payment object. If the RFI was created asynchronously, you must retrieve the full object using the [get details for an RFI endpoint](/api-reference/cpn/cpn-platform/get-rfi). The following is an example RFI object: ```json JSON theme={null} { "id": "48dfd36c-cf6c-4d9d-b065-69bdbe9bfea1", "paymentId": "90dfd86c-cf6c-4d9d-b065-69bdbe9bfec8", "status": "INFORMATION_REQUIRED", "level": "LEVEL_1", "expireDate": "2025-01-28T19:41:33.076Z", "fieldRequirements": { "version": 1, "schema": { "$schema": "https://json-schema.org/draft/2020-12/schema", "title": "RFI Requirements", "type": "object", "description": "RFI Requirements", "properties": { "DATE_OF_BIRTH": { "description": "Individual's date of birth (YYYY-MM-DD)", "type": "string" }, "NAME": { "description": "Individual's full name", "type": "string" } }, "required": ["NAME", "DATE_OF_BIRTH"] } }, "fileRequirements": [ { "fileName": "PROOF_OF_ADDRESS", "required": false }, { "fileName": "ORG_STRUCTURE", "required": false } ], "certificate": { "id": "0cc3c5fe-fa88-4e79-b5eb-1c5194a19b08", "certPem": "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", "domain": "api.circle.com", "jwk": { "kty": "EC", "crv": "P-256", "kid": "263521881931753643998528753619816524468853605762", "x": "YdjOeAmlNfWV0xIryFAivcp9of21s0c-JhyGEOINV2Y", "y": "n621ve_OV_p3jdocxtNkAk4uaKcYR2XWYUu1NMzBei8" } } } ``` ### Step 2: Create the RFI response You must provide all of the fields that are marked as required. Circle recommends providing the fields marked as optional for the highest likelihood of an approved RFI. If you do not have the requested information about the sender, you should request it. Once you have all of the required information, you can create the RFI response. Format it into the appropriate JSON format, based on the schema provided in the `fieldRequirements` parameter. Before encrypting and sending the response, you should validate the JSON response object against the JSON schema. See [How-to: Integrate with JSON Schema](/cpn/guides/payments/integrate-with-json-schema) for more information. The following is an example RFI response: ```json JSON theme={null} { "ADDRESS": { "city": "San Francisco", "country": "US", "postalCode": "94105", "stateProvince": "CA", "street": "123 Market Street" }, "NAME": "Alice Johnson", "DATE_OF_BIRTH": "1990-10-10", "NATIONAL_IDENTIFICATION_NUMBER": "12-9483432", "SOURCE_OF_FUNDS": "Company revenue", "METHOD_OF_VERIFICATION": "Electronic" } ``` ### Step 3: Encrypt the RFI response The RFI response must be encrypted before it is sent to the BFI. It is encrypted in the same manner as the travel rule and beneficiary account data. For a full guide on the encryption process, see [How-to: Encrypt Travel Rule and Beneficiary Account Data](/cpn/guides/payments/encrypt-travel-rule-beneficiary-data). ### Step 4: Submit the RFI response Submit the encrypted RFI response with the [submit RFI data endpoint](/api-reference/cpn/cpn-platform/submit-rfi) . The request should include the encrypted data and the version of the RFI JSON Schema. The version should match the version in the `fieldRequirements` parameter of the RFI object. An example request body is shown below: ```json JSON theme={null} { "rfi": { "version": 1, "data": "eyJhbGciOiJFQ0RILUVTK0ExMjhLVyIsImVuYyI6IkExMjhHQ00iLCJlcGsiOnsiY3J2IjoiUC0yNTYiLCJrdHkiOiJFQyIsIngiOiJ4ZzFRelVtaFRGdWV0Ti1Qd0N5dzdfRXd4SldKdk9ZTTFRLTNBRXFxZHdzIiwieSI6IjA0Z0dFMEsyT2ttVVZTMlhFUXZvR2hBUkJLWHQyWGRDRnRDNXpRMjQ3ajQifX0.Zaev1iHNNwG9_x0l3nwBcYlWBmlW9fP3.fmd2QQL_xKswDntW.1lYKjSoBZ_j7SKH4Q-kV8Zajcurh_zow1_e07zegfDNNEQ3DhsURPrjhDhyngtBe86T-WmDBM20j_1aChh1xwOS2vgKc-Kcv_4cNUzz0398ngYf2_xkEfvVckEexpX84omj5lmfqa0aleIQGldUVSuVV8fBl4YnH2oik5kDgvvQ4ap4MYhSTRqYJsi0bm6col7buPhnQJpojAjpp3ttoCYuOxbuDs5V_eNLIGuHPxF9KK7hS-l0qjLnNPcTnCbLL_fIveButXOzU54qB6lLssrE86O4xCH_d47_PAtaxJ296qtjGIB02dLSlrnORbVnvjrn17dhf8DmhkMy5GmFgtTs.TcOP8NKlgtgEaakORE1lXQ" } } ``` ### Step 5: Upload required files If the RFI includes a `fileRequirements` field, you must upload documentation about the sender in addition to submitting the RFI response. Files must be encrypted and uploaded one at a time to the [upload RFI file endpoint](/api-reference/cpn/cpn-platform/upload-rfi-file). You can upload files before or after submitting the RFI response, as long as it is before the RFI decision is made. See [How-to: Encrypt Files for RFI Transmission](/cpn/guides/payments/encrypt-files) for more information on how to encrypt files. The [upload RFI file endpoint](/api-reference/cpn/cpn-platform/upload-rfi-file) accepts a `multipart/form-data` request body in three parts. The request body should include the encrypted file, the encryption details, and the file metadata. The file metadata should include the filename, file type, and file key. The file key should match the `fileKey` in the `fileRequirements` field of the RFI object. The following is an example request body: ```text Text theme={null} ------WebKitFormBoundary Content-Disposition: form-data; name="fileMetadata" Content-Type: application/json { "fileName": "example.pdf", "fileType": "application/pdf", "fileKey": "PROOF_OF_ADDRESS" } ------WebKitFormBoundary Content-Disposition: form-data; name="encryption" Content-Type: application/json { "encryptedAesKey": "", "iv": ""} ------WebKitFormBoundary Content-Disposition: form-data; name="encryptedFile"; filename="encrypted_data.bin" Content-Type: application/octet-stream [BINARY FILE DATA] ``` Once you submit the RFI response, you receive the decision on the RFI via webhook. If the BFI approves the RFI, you can continue with the payment, or create a new payment for the sender if the existing payment has expired.