> ## 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: Deposit fiat
> Link a bank account and deposit fiat to mint USDC or EURC in your Circle Mint account.
Deposit fiat (onramp) from an external bank account to mint USDC or EURC in your
Circle Mint balance. The `/wires` endpoint supports multiple payment rails,
including standard wires (FedWire and SWIFT), real-time interbank rails (RTP,
SPEI, SEPA, and CHATS) where available, and book transfers when you bank with
one of Circle's settlement partners.
This guide focuses on standard wire deposits. The same endpoint handles other
rails -- Circle routes the deposit based on your linked bank and region.
Rail-specific parameters and additional endpoints (such as CUBIX and PIX for
local currencies) are out of scope here.
## Prerequisites
Before you begin:
* Complete the
[account and API key setup](/circle-mint/quickstarts/getting-started).
* Have access to a bank account that can send wire transfers.
## Step 1. Link a bank account
Use the
[create a wire bank account](/api-reference/circle-mint/account/create-business-wire-account)
endpoint to register your external bank account with Circle Mint.
```bash theme={null}
curl -X POST https://api-sandbox.circle.com/v1/businessAccount/banks/wires \
-H "Authorization: Bearer ${YOUR_API_KEY}" \
-H "Content-Type: application/json" \
-d '{"idempotencyKey":"ba943ff1-ca16-49b2-ba55-1057e70ca5c7","accountNumber":"12340010","routingNumber":"121000248","billingDetails":{"name":"Satoshi Nakamoto","city":"Boston","country":"US","line1":"100 Money Street","district":"MA","postalCode":"01234"},"bankAddress":{"bankName":"SAN FRANCISCO","city":"SAN FRANCISCO","country":"US","line1":"100 Money Street","district":"CA"}}'
```
Expected response:
```json theme={null}
{
"data": {
"id": "9d1fa351-b24d-442a-8aa5-e717db1ed636",
"status": "pending",
"description": "WELLS FARGO BANK, NA ****0010",
"trackingRef": "CIR2GKYL4B",
"virtualAccountEnabled": true,
"billingDetails": {
"name": "Satoshi Nakamoto",
"line1": "100 Money Street",
"city": "Boston",
"postalCode": "01234",
"district": "MA",
"country": "US"
},
"bankAddress": {
"bankName": "WELLS FARGO BANK, NA",
"line1": "100 Money Street",
"city": "SAN FRANCISCO",
"district": "CA",
"country": "US"
},
"createDate": "2023-11-04T20:02:21.062Z",
"updateDate": "2023-11-04T20:02:21.062Z"
}
}
```
Record the `id` and `trackingRef` values from the response. You use both in the
following steps.
## Step 2. Retrieve wire instructions
Use the
[get wire instructions](/api-reference/circle-mint/account/get-business-wire-account-instructions)
endpoint to fetch the beneficiary details your bank needs to send the wire.
```bash theme={null}
curl https://api-sandbox.circle.com/v1/businessAccount/banks/wires/${BANK_ACCOUNT_ID}/instructions \
-H "Authorization: Bearer ${YOUR_API_KEY}"
```
Expected response:
```json theme={null}
{
"data": {
"trackingRef": "CIR22FEP33",
"beneficiary": {
"name": "CIRCLE INTERNET FINANCIAL INC",
"address1": "1 MAIN STREET",
"address2": "SUITE 1"
},
"virtualAccountEnabled": true,
"beneficiaryBank": {
"name": "CRYPTO BANK",
"address": "1 MONEY STREET",
"city": "NEW YORK",
"postalCode": "1001",
"country": "US",
"swiftCode": "CRYPTO99",
"routingNumber": "999999999",
"accountNumber": "123815146304",
"currency": "USD"
}
}
}
```
The response includes:
* **Beneficiary details** -- the name and address of the recipient (Circle).
* **Routing information** -- the bank name, SWIFT code, and routing number for
the beneficiary bank.
* **Virtual Account Number** -- the `beneficiaryBank.accountNumber` field,
unique to your linked bank account.
* **Tracking reference** -- the `trackingRef` value to include in the wire memo.
### Virtual account numbers
Not all Circle settlement banks support Virtual Account Numbers. When
`virtualAccountEnabled` is `true` in the wire instructions response, the linked
bank account has a unique VAN in the `beneficiaryBank.accountNumber` field. When
the sender includes the VAN as the account number on their wire, the tracking
reference in the wire memo becomes optional.
When `virtualAccountEnabled` is `false`, the sender must include the
`trackingRef` in the wire memo so Circle can match the deposit to your account.
Benefits of using a VAN (where supported):
* Eliminates the need for senders to include tracking references in payment
instructions.
* Reduces wire returns caused by missing or incorrect tracking references.
* Supports all wire types: domestic, international, and SWIFT.
## Step 3. Send the wire deposit
In production, initiate the wire transfer from your bank using the instructions
returned in Step 2. Confirm that the wire details -- beneficiary name, account
number, and routing number -- match exactly. Mismatched details can result in
wire returns or processing delays of several business days.
Domestic wire deposits received before the daily cutoff typically settle on the
same business day. International wires may take longer depending on intermediary
banks.
### Simulate a deposit in sandbox
In the sandbox environment, use the
[mock wire payment](/api-reference/circle-mint/account/create-mock-wire-payment)
endpoint to simulate a wire deposit without sending real funds. Provide the
`trackingRef` from Step 2 and the `beneficiaryBank.accountNumber` (the VAN) from
the wire instructions response.
```bash theme={null}
curl -X POST https://api-sandbox.circle.com/v1/mocks/payments/wire \
-H "Authorization: Bearer ${YOUR_API_KEY}" \
-H "Content-Type: application/json" \
-d '{"amount":{"amount":"50.00","currency":"USD"},"trackingRef":"CIR22FEP33","beneficiaryBank":{"accountNumber":"123815146304"}}'
```
Expected response:
```json theme={null}
{
"data": {
"trackingRef": "CIR22FEP33",
"amount": {
"amount": "50.00",
"currency": "USD"
},
"beneficiaryBank": {
"accountNumber": "123815146304"
},
"status": "pending"
}
}
```
The mock wire endpoint is available in sandbox only. Mock wire deposits
process in batches and may take up to 15 minutes to complete.
## Step 4. Verify the deposit
Use the
[list deposits](/api-reference/circle-mint/account/list-business-deposits)
endpoint to confirm the incoming fiat deposit has settled.
```bash theme={null}
curl https://api-sandbox.circle.com/v1/businessAccount/deposits \
-H "Authorization: Bearer ${YOUR_API_KEY}"
```
Expected response:
```json theme={null}
{
"data": [
{
"id": "b8627ae8-732b-4d25-b947-1df8f4007a29",
"sourceWalletId": "1000066041",
"destination": {
"type": "wallet",
"id": "1000066041"
},
"amount": {
"amount": "50.00",
"currency": "USD"
},
"status": "complete",
"createDate": "2024-01-01T12:00:00.000Z"
}
]
}
```
## See also
* [How minting and redemption works](/circle-mint/concepts/how-minting-works) --
understand the minting process
* [Sandbox to Production](/circle-mint/references/sandbox-and-testing) --
transition to production
* [Create a wire bank account](/api-reference/circle-mint/account/create-business-wire-account)
\-- API reference