> ## 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.
# Supported chains and currencies
> Blockchains and currencies supported by Circle Mint and related APIs.
**Unsupported assets**
Circle Mint and Circle APIs only support USDC and EURC tokens on the indicated
blockchains. Don't send unsupported tokens such as USDT or bridged USDC to your
Circle Mint address. Doing so might result in a loss of funds.
**Cosmos appchains**
Circle Mint and Circle APIs only support USDC from Noble. If you transfer USDC
from Noble to other appchains via IBC (Inter-Blockchain Communication), you must
transfer it back to Noble before you transfer it to your Circle Mint address.
Don't attempt to deposit USDC from an appchain other than Noble to your Circle
Mint address. Doing so might result in a loss of funds.
**Polkadot parachains**
Circle Mint and Circle APIs only support USDC from Polkadot Asset Hub. If you
transfer USDC from Polkadot Asset Hub to other parachains via XCM, you must
transfer it back to Polkadot Asset Hub before you transfer it to your Circle
Mint address.
Don't attempt to deposit XCM-transferred USDC from a parachain other than
Polkadot Asset Hub to your Circle Mint address. Doing so might result in a loss
of funds.
**Injective**
Circle Mint only supports USDC deposits on Injective through the EVM layer.
Cosmos-layer USDC deposits are not supported. If you deposit USDC through the
Cosmos layer, your funds are stuck and not credited to your Circle Mint account.
To recover stuck funds, contact
[Circle Support](https://help.circle.com/s/submit-ticket).
## USDC
| Chain | API Chain Code | API Currency Code |
| - | - | - |
| Algorand | `ALGO` | `USD` |
| Aptos | `APTOS` | `USD` |
| Arbitrum | `ARB` | `USD` |
| Arc | `ARC` | `USD` |
| Avalanche C-Chain | `AVAX` | `USD` |
| Base | `BASE` | `USD` |
| Celo | `CELO` | `USD` |
| Codex | `CODEX` | `USD` |
| Cronos | `CRONOS` | `USD` |
| EDGE | `EDGE` | `USD` |
| Ethereum | `ETH` | `USD` |
| Hedera | `HBAR` | `USD` |
| HyperEVM | `HYPEREVM` | `USD` |
| Injective | `INJECTIVE` | `USD` |
| Ink | `INK` | `USD` |
| Linea | `LINEA` | `USD` |
| Monad | `MONAD` | `USD` |
| Morph | `MORPH` | `USD` |
| NEAR | `NEAR` | `USD` |
| Noble | `NOBLE` | `USD` |
| OP Mainnet | `OP` | `USD` |
| Pharos | `PHAROS` | `USD` |
| Plasma | `PLASMA` | `USD` |
| Plume | `PLUME` | `USD` |
| Polkadot Asset Hub | `PAH` | `USD` |
| Polygon PoS | `POLY` | `USD` |
| Sei | `SEI` | `USD` |
| Solana | `SOL` | `USD` |
| Sonic | `SONIC` | `USD` |
| Starknet | `STRK` | `USD` |
| Stellar | `XLM` | `USD` |
| Sui | `SUI` | `USD` |
| Unichain | `UNI` | `USD` |
| World Chain | `WORLDCHAIN` | `USD` |
| X Layer | `XLAYER` | `USD` |
| XDC | `XDC` | `USD` |
| XRPL | `XRP` | `USD` |
| ZKsync Era | `ZKS` | `USD` |
## EURC
| Chain | API Chain Code | API Currency Code |
| - | - | - |
| Arc | `ARC` | `EUR` |
| Avalanche C-Chain | `AVAX` | `EUR` |
| Base | `BASE` | `EUR` |
| Cronos | `CRONOS` | `EUR` |
| Ethereum | `ETH` | `EUR` |
| Plasma | `PLASMA` | `EUR` |
| Solana | `SOL` | `EUR` |
| Stellar | `XLM` | `EUR` |
| World Chain | `WORLDCHAIN` | `EUR` |
## cirBTC
| Chain | API Chain Code | API Currency Code |
| - | - | - |
| Arc | `ARC` | `CIRBTC` |
| Ethereum | `ETH` | `CIRBTC` |
For an overview of cirBTC and how it works, see
[cirBTC overview](/assets/what-is-cirbtc).
## Using chains and currencies in the API
Any time you refer to a currency in a Circle Mint API call, you use a currency
and chain pair. For example, to
[create a USDC transfer](/api-reference/circle-mint/account/create-business-transfer)
on Ethereum, specify the `USD` currency on the `ETH` chain.
When referring to balances, you only need to refer to the currency because the
value of the currency for Circle-hosted assets is independent of the chain.