> ## 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: Repay a loan > Repay part or all of an open loan's outstanding USDC debt and release your cirBTC collateral back to your Circle Mint balance. You can repay a loan in full or in part. Full repayment closes the loan and releases the cirBTC collateral back to your Circle Mint balance. Partial repayment reduces the outstanding debt without closing the loan or releasing collateral. See [How Digital Asset-Backed Borrowing works](/circle-mint/concepts/digital-asset-backed-borrowing) for the underlying concepts. ## Prerequisites Before you begin, ensure that you've: * Completed the [Borrow USDC against cirBTC collateral](/circle-mint/quickstarts/borrow-with-cirbtc) quickstart and hold at least one loan in `active` status. * Held sufficient USDC in your Mint balance to cover the repayment amount you plan to submit. ## Steps Decide whether you want to repay in full or partially, then call [`POST /v1/borrow/loans/{id}/repayments`](/api-reference/circle-mint/digital-asset-backed-borrowing/create-borrow-repayment) with the corresponding `mode`. * **Full repay**: set `mode: FULL`. Circle measures the outstanding debt at the moment it builds the UserOperation and repays that exact amount. On success, Circle releases the loan's cirBTC collateral back to your Mint balance and the loan transitions to `closed`. * **Partial repay**: set `mode: PARTIAL` and include the `amount` you want to apply in raw `uint256` base units. The loan stays `active` with a reduced debt. No collateral is released. ```bash theme={null} curl -X POST https://api-sandbox.circle.com/v1/borrow/loans/fc988ed5-c129-4f70-a064-e5beb7eb8e32/repayments \ -H "Authorization: Bearer $API_KEY" \ -H "Content-Type: application/json" \ -d '{ "idempotencyKey": "d7a3e2c1-8f45-4b91-ae67-2c9d0f8b3e5a", "mode": "FULL" }' ``` ```bash theme={null} curl -X POST https://api-sandbox.circle.com/v1/borrow/loans/fc988ed5-c129-4f70-a064-e5beb7eb8e32/repayments \ -H "Authorization: Bearer $API_KEY" \ -H "Content-Type: application/json" \ -d '{ "idempotencyKey": "d7a3e2c1-8f45-4b91-ae67-2c9d0f8b3e5a", "mode": "PARTIAL", "amount": "50000000000" }' ``` The endpoint returns an `onchainJob` with `jobType: repay`: ```json theme={null} { "data": { "id": "e5f6a7b8-9012-3456-efab-345678901234", "jobType": "repay", "status": "received", "createDate": "2026-06-25T10:00:00.000Z", "updateDate": "2026-06-25T10:00:00.000Z" } } ``` Save the job `id`. You poll it in the next step. Circle builds, signs, and submits the onchain UserOperation for the repayment. The job progresses through `submitted` and `confirmed` to `completed`. Poll [`GET /v1/borrow/jobs/{id}`](/api-reference/circle-mint/digital-asset-backed-borrowing/get-borrow-job) until you see the terminal state. ```json theme={null} { "data": { "id": "e5f6a7b8-9012-3456-efab-345678901234", "jobType": "repay", "status": "completed", "amount": "500.00", "asset": "USD", "loanId": "fc988ed5-c129-4f70-a064-e5beb7eb8e32", "txHash": "0x2b3c4d5e6f70819293a4b5c6d7e8f90a1b2c3d4e5f60718293a4b5c6d7e8f9aa", "createDate": "2026-06-25T10:00:00.000Z", "updateDate": "2026-06-25T10:02:00.000Z" } } ``` Fetch the loan to inspect the updated position: ```bash theme={null} curl https://api-sandbox.circle.com/v1/borrow/loans/fc988ed5-c129-4f70-a064-e5beb7eb8e32 \ -H "Authorization: Bearer $API_KEY" ``` For a full repay, the loan's `status` is `closed` and `debtAmount` is zero. The cirBTC collateral is credited back to your Mint balance. Confirm the credit by calling `GET /v1/businessAccount/balances`. For a partial repay, the loan's `status` remains `active` and `debtAmount` reflects the reduced outstanding balance. No collateral change occurs.