> ## 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 - Mint - 2026
> 2026 release notes for Mint
## October 2026
### API additions
Added
[`GET /v1/businessAccount/wallets/addresses/vasps`](/api-reference/circle-mint/account/list-business-recipient-vasps)
for listing the VASPs you can use when creating hosted-custody recipients.
### Deprecation notice
Webhooks v1 are deprecated and being phased out. Migrate existing integrations
to [webhooks v2](/api-reference/webhook-endpoints).
## September 2026
### Documentation additions
Launched Circle Match, a batch-auction venue where eligible Circle Mint
customers can match USDC mint and burn demand.
* [Circle Match](/circle-match)
* [Place your first order](/circle-match/quickstarts/place-your-first-order)
* [WebSocket reference](/circle-match/references/websocket-reference)
* [API reference](/api-reference/circle-match/all/place-order)
### API additions
Added the following payout Request for Information (RFI) endpoints:
* [`GET /v1/payouts/{id}/rfi`](/api-reference/circle-mint/payouts/get-payout-rfi)
* [`POST /v1/payouts/{id}/rfi/submit`](/api-reference/circle-mint/payouts/submit-payout-rfi)
* [`POST /v1/payouts/{id}/rfi/files`](/api-reference/circle-mint/payouts/upload-payout-rfi-files)
### Documentation additions
Launched **Digital Asset-Backed Borrowing** in Circle Mint. Institutions can now
borrow USDC against digital-asset collateral (starting with cirBTC) through a
new `/v1/borrow/*` API, an admin approval workflow, and a modular smart contract
custody wallet.
* [Digital Asset-Backed Borrowing overview](/circle-mint/concepts/digital-asset-backed-borrowing)
* [Quickstart: Borrow USDC against cirBTC](/circle-mint/quickstarts/borrow-with-cirbtc)
* [Repay a loan](/circle-mint/howtos/repay-loan)
* [Add collateral](/circle-mint/howtos/add-collateral)
* [Add a wallet owner](/circle-mint/howtos/add-wallet-owner)
* [API reference](/api-reference/circle-mint/digital-asset-backed-borrowing/create-borrow-wallet)
### Blockchain expansion
Added Arc mainnet as a supported blockchain for Circle Mint.
Updated topics:
* [Supported chains and currencies](/circle-mint/references/supported-chains-and-currencies)
* [Blockchain confirmations](/circle-mint/references/blockchain-confirmations)
* [Travel Rule compliance](/circle-mint/references/travel-rule-compliance)
## August 2026
Added support for Circle Mint on Plasma (API chain code `PLASMA`).
### Documentation updates
* [Supported chains and currencies](/circle-mint/references/supported-chains-and-currencies)
* [Blockchain confirmations](/circle-mint/references/blockchain-confirmations)
Added support for Circle Mint on X Layer (API chain code `XLAYER`).
### Documentation updates
* [Supported chains and currencies](/circle-mint/references/supported-chains-and-currencies)
* [Blockchain confirmations](/circle-mint/references/blockchain-confirmations)
## July 2026
### New features
Added mutual TLS (mTLS) authentication for Circle Mint customers operating in
the EU/EEA under the Markets in Crypto-Assets (MiCA) regulation. When mTLS is
enabled, API requests are authenticated with both an API key and a Circle-issued
client certificate, and all traffic must use the regional EU hostname
`api-eu.circle.com`. Enabling mTLS revokes existing API keys, and new keys carry
a 180-day maximum lifetime.
* [How mTLS authentication works](/circle-mint/mtls-authentication)
* [How-to: Set up mTLS authentication](/circle-mint/set-up-mtls-authentication)
* [How-to: Rotate your mTLS API key](/circle-mint/rotate-mtls-api-key)
* [How-to: Rotate your mTLS client certificate](/circle-mint/rotate-mtls-certificate)
Documented the full set of `riskEvaluation.reason` codes returned when Circle's
risk engine acts on a payment, payout, or transfer. Use these codes to
understand why a transaction was blocked and to build appropriate handling in
your integration.
* [Risk evaluation reason codes](/circle-mint/references/error-codes#risk-evaluation-reason-codes)
## June 2026
Added support for USDC and EURC on Cronos mainnet through Circle Mint, using the
`CRONOS` API chain code. For chain codes and confirmation times, see
[Supported chains and currencies](/circle-mint/references/supported-chains-and-currencies)
and
[Blockchain confirmations](/circle-mint/references/blockchain-confirmations).
## May 2026
### cirBTC support
cirBTC (Circle Wrapped Bitcoin) is now available through the Circle Mint API.
cirBTC is a tokenized representation of Bitcoin issued on Ethereum, backed 1:1
by native BTC held at a regulated entity in the Circle group. Reserves are
verified onchain in real time through
[Chainlink Proof of Reserves](https://chain.link/proof-of-reserve).
No new API endpoints are required—existing Circle Mint endpoints accept `CIRBTC`
as a currency code alongside `USD` and `EUR`.
### Documentation additions
* [cirBTC overview](/assets/what-is-cirbtc)
* [Quickstart: Mint and redeem cirBTC](/circle-mint/quickstarts/mint-and-redeem-cirbtc)
### Documentation updates
* [Supported Chains and Currencies](/circle-mint/references/supported-chains-and-currencies)—added
cirBTC section with the Ethereum (`ETH`) blockchain code
### Documentation updates
Rewrote the Circle Mint documentation to improve onboarding, product framing,
quickstarts, and core reference material for supported chains, countries, and
sandbox testing.
The following topics were added or updated:
* [Set Up Your Mint Account](/circle-mint/quickstarts/getting-started)
* [Quickstart: Mint and Redeem USDC](/circle-mint/quickstarts/mint-and-redeem)
* [How stablecoin payins and payouts work](/cpn/stablecoin-payments/concepts/how-stablecoin-payments-work)
* [Supported Chains and Currencies](/circle-mint/references/supported-chains-and-currencies)
* [Supported countries](/circle-mint/references/supported-countries)
* [Sandbox and Testing](/circle-mint/references/sandbox-and-testing)
## April 2026
### Documentation additions
Added the following new topic for treasury reconciliation workflows:
* [CAMT.053 Daily Statements for Reconciliation](/circle-mint/references/camt053-statements)
**Crypto Payouts** and **Crypto Address Book** docs now include Singapore
(**CIRCLE\_SG**) coverage. They add Travel Rule notes, payment reason codes, and
`VASP` data for hosted custody.
### Documentation additions
* [Payment reason codes (Travel Rule reference)](/circle-mint/references/travel-rule-compliance#payment-reason-codes)
### Documentation updates
* **Crypto Payouts API:** Documented `purposeOfTransfer` on create and get.
Singapore (**CIRCLE\_SG**) customers must send a payment reason code to create
a payout.
* **Crypto Address Book API:** Documented request and response shapes for
General and Singapore (**CIRCLE\_SG**) customer entities.
Continuous payment intents are now the default type when
[creating a payment intent](/api-reference/circle-mint/payments/create-payment-intent).
### Documentation additions
Added the following new topic to explain how stablecoin payins and payouts work,
including continuous and transient payment intents:
* [How stablecoin payins and payouts work](/cpn/stablecoin-payments/concepts/how-stablecoin-payments-work)
### Documentation updates
Updated the following quickstarts to align terminology and structure with the
stablecoin payins and payouts flow, and to make the steps easier to follow
end-to-end:
* [How-to: Receive a stablecoin payin](/cpn/stablecoin-payments/howtos/receive-stablecoin-payin)
(formerly "Quickstart: Crypto Deposits")
* [How-to: Refund a stablecoin payin](/cpn/stablecoin-payments/howtos/refund-stablecoin-payin)
(formerly "Quickstart: Crypto Refunds")
* [How-to: Send a stablecoin payout](/cpn/stablecoin-payments/howtos/send-stablecoin-payout)
(formerly "Send USDC from your Circle Mint Account")
Launched the Credit API, enabling programmatic access to Settlement Advance and
Line of Credit products. You can now initiate draws, track transfer status,
manage fees, and process repayments through endpoints under `/v1/credit/`.
### Documentation updates
Added the following topics for the Credit API:
* [Credit API Overview](/circle-mint/concepts/credit-api)
* [Quickstart: Settlement Advance](/circle-mint/quickstarts/settlement-advance)
* [Quickstart: Line of Credit](/circle-mint/quickstarts/line-of-credit)
## March 2026
Added support for USDC on the Morph blockchain.
### Documentation updates
Updated the following topics to reflect USDC support on Morph:
* [Supported Chains and Currencies](/circle-mint/references/supported-chains-and-currencies)
* [Blockchain confirmations](/circle-mint/references/blockchain-confirmations)
Added support for USDC on the EDGE blockchain.
### Documentation updates
Updated the following topics to reflect USDC support on EDGE:
* [Supported Chains and Currencies](/circle-mint/references/supported-chains-and-currencies)
* [Blockchain confirmations](/circle-mint/references/blockchain-confirmations)