> ## 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. # Account structure > Understand the account hierarchy, roles, and subaccount model in Digital Asset Accounts The Digital Asset Accounts hierarchy organizes funds across programs, accounts, and subaccounts. This structure enables regulatory segregation, per-entity compliance tracking, and clear fund ownership under the [Direct End-User Custody model](/digital-asset-accounts/concepts/custody-model). ## Roles Digital Asset Accounts defines two primary roles: | Role | Description | | - | - | | **Distributor** | A fintech, platform, or marketplace that integrates with the Digital Asset Accounts API to offer stablecoin-backed account services to their customers. Distributors do not hold custody of funds. | | **End customer** | A business entity onboarded through the distributor. Each end customer is verified by Circle through KYB (Know Your Business) and receives a dedicated account. | ## Account hierarchy Digital Asset Accounts organizes funds across three levels: * **Program**: The top-level container for a distributor's integration. When Circle provisions your API access, your credentials are scoped to a specific program, and all accounts and transactions in your integration belong to that program. * **Account**: Each onboarded business entity receives an account under your program. The account is the primary identity for the end customer in Digital Asset Accounts. Circle performs KYB verification before activating an account, and each account receives a risk tier that determines its [transaction limits](/digital-asset-accounts/concepts/limits-and-risk-ratings). * **Subaccount**: Each account contains one or more subaccounts. Each subaccount holds a balance in a specific currency (for example, USDC or EURC) and is created automatically when an account is provisioned. Subaccounts serve as the unit for: * **Balance tracking**: Each subaccount maintains its own balance in a single currency. * **Transaction history**: Deposits, [wire withdrawals](/digital-asset-accounts/howtos/wire-deposits-and-withdrawals), and transfers are recorded against specific subaccounts. * **Internal transfers**: Funds move between subaccounts in the same program instantly and at no cost. ## Onboarding flow End-customer onboarding involves three stages: 1. **Business information submission**: The distributor submits the business entity's information using the [End User Onboarding API](/end-user-onboarding). The API provides a JSON Schema that defines required fields, supports bulk data submission, and handles document uploads. Required details include the business name, registration, and beneficial owners. 2. **KYB verification**: Circle reviews the submitted information and performs compliance checks. If the compliance team needs additional data, the application moves to `PENDING_CUSTOMER_INFORMATION` and the distributor can respond through the API. See [Handle requests for information](/end-user-onboarding/howtos/handle-rfis) for details. 3. **Account activation**: After KYB is approved, Circle activates the account and provisions subaccounts for the supported currencies. The account is then ready to receive deposits and perform transactions. ## API key scoping Your API key is scoped to your program, which means: * You can only access accounts and transactions in your own program * All API operations are automatically restricted to your program's scope * You cannot access accounts belonging to other distributors This scoping ensures data isolation between distributors while allowing full visibility into your own end customers' accounts and transactions.