> ## 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.
# Release notes - Circle Payments Network - 2025
> 2025 release notes for Circle Payments Network
## August 2025
### Documentation additions
* Added a topic on detailed
[payment failure codes](/cpn/references/errors/payment-failure-codes) to help
explain why a payment failed and how to resolve the issue
### Documentation updates
* Updated
[payment failure reasons](/cpn/references/errors/payment-and-transaction-failure-reasons#payments)
with new values
* Added new [magic values](/cpn/references/testing/magic-values) for testing
refund workflows
* Added a new [payment error code](/cpn/references/errors/error-codes#payment)
(`290207`) for missing required parameters
* Added new [RFI error codes](/cpn/references/errors/error-codes#rfi) (`290302`,
`290303`, `290304`, `290305`) for RFI verification failures
### API updates
* Added the optional `quoteOptions` field to the
[`POST /v1/cpn/quotes`](/api-reference/cpn/cpn-platform/create-quotes)
endpoint to support additional quote options when creating a quote.
* Updated the allowed values for `failureReason` for payments and transactions
to reflect new failure reasons.
* Added `failureCode` to the response of the following endpoints:
* [`POST /v1/cpn/payments`](/api-reference/cpn/cpn-platform/create-payment)
* [`GET /v1/cpn/payments`](/api-reference/cpn/cpn-platform/list-payments)
* [`GET /v1/cpn/payments/{paymentId}`](/api-reference/cpn/cpn-platform/get-payment)
## July 2025
Added full DevDocs for OFIs for Circle Payments network:
### Documentation additions
Added the following topics for CPN:
* [CPN overview](/cpn)
* [API Integration Concepts](/cpn/concepts/api/api-integration)
* [Quickstart: Integrate with CPN as an OFI](/cpn/quickstarts/integrate-with-cpn-ofi)
* [How-to: Set up a webhook endpoint](/api-reference/webhook-endpoints)
* [How-to: Verify webhook signatures](/api-reference/verify-webhook-signatures)
* [How-to: Request Payment Configurations and Routes](/cpn/guides/payments/request-payment-config)
* [How-to: Integrate with JSON Schema](/cpn/guides/payments/integrate-with-json-schema)
* [How-to: Encrypt Travel Rule and Beneficiary Data](/cpn/guides/payments/encrypt-travel-rule-beneficiary-data)
* [How-to: Create an Onchain Transaction](/cpn/guides/transactions/create-an-onchain-txn)
* [How-to: Encrypt Files for RFI Transmission](/cpn/guides/payments/encrypt-files)
* [How-to: Create a Support Ticket](/cpn/guides/supports/create-support-ticket)
* [Supported blockchains](/cpn/references/blockchains/supported-blockchains)
* [Wallet provider compatibility](/cpn/references/blockchains/wallet-provider-compatibility)
* [Component states and workflows](/cpn/concepts/payments/component-states-and-workflows)
* [Magic values for testing](/cpn/references/testing/magic-values)
* [Webhook events](/cpn/references/webhooks/webhook-events)
* [Webhook retries](/cpn/concepts/webhooks/webhook-retries)
* [Payment and transaction failure reasons](/cpn/references/errors/payment-and-transaction-failure-reasons)
* [Error codes](/cpn/references/errors/error-codes)
* [JSON Schema](/cpn/concepts/api/json-schema)
* [RFI levels](/cpn/references/compliance/rfi-levels)
* [Travel rule requirements](/cpn/references/compliance/travel-rule-requirements)
* [Payment reference](/cpn/concepts/payments/payment-reference)
* [Validating Brazilian tax ID and bank account numbers](/cpn/references/compliance/validating-brazil-tax-account-id)
### API additions
Added the following CPN endpoints:
* [`GET /v1/cpn/configurations/overview`](/api-reference/cpn/cpn-platform/get-payment-configurations-overview)
* [`GET /v1/cpn/configurations/routes`](/api-reference/cpn/cpn-platform/list-routes)
* [`POST /v1/cpn/quotes`](/api-reference/cpn/cpn-platform/create-quotes)
* [`GET /v1/cpn/quotes/{quoteId}`](/api-reference/cpn/cpn-platform/get-quote)
* [`GET /v1/cpn/payments`](/api-reference/cpn/cpn-platform/list-payments)
* [`POST /v1/cpn/payments`](/api-reference/cpn/cpn-platform/create-payment)
* [`GET /v1/cpn/payments/{paymendId}`](/api-reference/cpn/cpn-platform/get-payment)
* [`GET /v1/cpn/payments/{paymentId}/refunds/{refundId}`](/api-reference/cpn/cpn-platform/get-refund)
* [`GET /v1/cpn/payments/requirements`](/api-reference/cpn/cpn-platform/get-payment-requirements)
* [`POST /v1/cpn/payments/{paymentId}/transactions`](/api-reference/cpn/cpn-platform/create-transaction)
* [`GET /v1/cpn/payments/{paymentId}/transactions/{transactionId}`](/api-reference/cpn/cpn-platform/get-transaction)
* [`POST /v1/cpn/payments/{paymentId}/transactions/{transactionId}/submit`](/api-reference/cpn/cpn-platform/submit-transaction)
* [`POST /v1/cpn/payments/{paymentId}/transactions/accelerate`](/api-reference/cpn/cpn-platform/accelerate-transaction)
* [`GET /v1/cpn/payments/{paymentId}/rfis/{rfiId}`](/api-reference/cpn/cpn-platform/get-rfi)
* [`POST /v1/cpn/payments/{paymentId}/rfis/{rfiId}/submit`](/api-reference/cpn/cpn-platform/submit-rfi)
* [`POST /v1/cpn/payments/{paymentId}/rfis/{rfiId}/files`](/api-reference/cpn/cpn-platform/upload-rfi-file)
* [`POST /v1/cpn/supportTickets`](/api-reference/cpn/cpn-platform/create-support-ticket)