> ## 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. # List all markets > Returns the allowlisted lending markets available to you, including current rates and LTV parameters. ## OpenAPI ````yaml openapi/digital-asset-backed-borrowing.yaml get /v1/borrow/markets openapi: 3.0.2 info: version: ${version} title: Digital Asset-Backed Borrowing API description: > The Digital Asset-Backed Borrowing API lets you borrow stablecoin liquidity against onchain collateral. It uses a dedicated wallet to hold collateral and borrowed funds, and Circle handles the onchain transactions. Write operations are asynchronous and return a job that can be polled for status. servers: - url: https://api-sandbox.circle.com - url: https://api.circle.com security: [] tags: - name: Borrow Wallets description: >- Provision and inspect the per-entity MSCA wallet that holds collateral and borrowed funds. - name: Borrow Loans description: Originate, inspect, repay, and add collateral to borrow positions. - name: Borrow Jobs description: Observe asynchronous onchain operations. - name: Borrow Markets description: Discover allowlisted lending markets. paths: /v1/borrow/markets: get: tags: - Borrow Markets summary: List all markets description: > Returns the allowlisted lending markets available to you, including current rates and LTV parameters. operationId: listBorrowMarkets responses: '200': description: Successfully retrieved a list of markets. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: title: ListBorrowMarketsResponse type: object properties: data: type: array items: $ref: '#/components/schemas/OnchainMarket' examples: response: value: data: - id: d24e8f01-2345-6789-abcd-ef0123456789 protocol: morpho displayName: cirBTC / USDC (Morpho Blue) marketId: >- 0x3a85e6f1c2d3b4a596877869504132e1d0c9b8a7766554433221100ffeeddccbb lltv: '0.86' maxOriginationLtv: '0.80' borrowApy: '0.0542' borrowAsset: USD collateralAsset: CIRBTC oraclePrice: '67234.512345' marketDataUpdateDate: '2026-06-24T12:00:00.000Z' isActive: true '401': $ref: '#/components/responses/NotAuthorized' '403': $ref: '#/components/responses/Forbidden' security: - bearerAuth: [] components: 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 schemas: OnchainMarket: type: object description: > An allowlisted lending market you can borrow from. Markets are curated by Circle and vary by environment. `oraclePrice` and `borrowApy` are read live from the protocol on each request. `marketDataUpdateDate` records when those values were read. required: - id - protocol - displayName - marketId - lltv - maxOriginationLtv - borrowApy - borrowAsset - collateralAsset - oraclePrice - marketDataUpdateDate - isActive properties: id: type: string format: uuid description: Unique identifier of this market configuration. protocol: type: string enum: - morpho description: Lending protocol. displayName: type: string description: Human-readable market name. example: cirBTC / USDC (Morpho Blue) marketId: type: string description: > Protocol-specific market identifier. For Morpho Blue, this is the market ID hash. Pass this value as `marketId` when creating a borrow. lltv: type: string description: >- Protocol-defined liquidation LTV (decimal string between `0.0` and `1.0`). maxOriginationLtv: type: string description: > Maximum LTV Circle allows at borrow creation, set stricter than `lltv` to provide a safety buffer against oracle drift. Decimal string between `0.0` and `1.0`. borrowApy: type: string description: >- Current annualized borrow rate, read live from the protocol on each request (decimal string). borrowAsset: type: string description: Circle currency code of the borrowed asset, such as `USD` for USDC. example: USD collateralAsset: type: string description: >- Circle currency code of the collateral asset, such as `CIRBTC` for cirBTC. example: CIRBTC oraclePrice: type: string description: | Price of one unit of the collateral asset, expressed in the borrowed asset (decimal string). Read live from the market's oracle on each request. Use this value to estimate LTV before submitting a borrow. example: '67234.512345' marketDataUpdateDate: type: string format: date-time description: > Date and time when `oraclePrice` and `borrowApy` were read from the market. This single timestamp applies to both fields, which are fetched together. isActive: type: boolean description: Whether the market is currently open for new borrows. example: id: d24e8f01-2345-6789-abcd-ef0123456789 protocol: morpho displayName: cirBTC / USDC (Morpho Blue) marketId: '0x3a85e6f1c2d3b4a596877869504132e1d0c9b8a7766554433221100ffeeddccbb' lltv: '0.86' maxOriginationLtv: '0.80' borrowApy: '0.0542' borrowAsset: USD collateralAsset: CIRBTC oraclePrice: '67234.512345' marketDataUpdateDate: '2026-06-24T12:00:00.000Z' isActive: true responses: 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. Forbidden: description: >- The request provides authentication, but the authenticated user does not possess sufficient permissions for accessing this resource. headers: X-Request-Id: $ref: '#/components/headers/XRequestId' content: application/json: schema: type: object title: Forbidden required: - code - message properties: code: type: integer example: 400 message: type: string example: Something went wrong. example: code: 3 message: Forbidden examples: response: value: code: 3 message: Forbidden securitySchemes: bearerAuth: type: http scheme: bearer ````