> ## 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. # CCTP Stellar contracts and interfaces > Contracts for CCTP support on the Stellar network ## Overview Stellar CCTP contracts run on Soroban, Stellar's smart contracts platform. CCTP message fields use 32-byte address encodings. CCTP treats `mintRecipient` as a contract address. If the recipient is a Stellar user or [muxed](https://developers.stellar.org/docs/build/guides/transactions/pooled-accounts-muxed-accounts-memos#muxed-accounts) account instead, hook data can carry a `forwardRecipient` `strkey` so the forwarder can send funds to that address. To align with Stellar address encoding while keeping parity with EVM and other non-EVM blockchains, CCTP uses three contracts: * `TokenMessengerMinter`: consolidates the responsibilities of `TokenMessengerV2` (burn + send) and `TokenMinterV2` (receive + mint). On mint, `mintRecipient` is treated as a contract address and hooks supply the `forwardRecipient` when needed. * `MessageTransmitter`: provides the messaging layer that emits or receives attested messages and delivers them to `TokenMessengerMinter` (including `receive_message` for forwarder flows). * `CctpForwarder`: receives minted USDC and forwards it to `forwardRecipient` in hook data. ## Mainnet contract addresses | Contract | [Domain](/cctp/concepts/supported-chains-and-domains#domain-identifiers) | Address | | :- | :- | :- | | `TokenMessengerMinter` | 27 | [`CAE2G5Z77UP7GYPYGFOWFGW7C7J6I4YP2AFGSADRKQY62SYUFLPNFTXL`](https://stellar.expert/explorer/public/contract/CAE2G5Z77UP7GYPYGFOWFGW7C7J6I4YP2AFGSADRKQY62SYUFLPNFTXL) | | `MessageTransmitter` | 27 | [`CACMENFFJPJMSDAJQLX4R7K3SFZIW2LJSE3R2UMLGSWHFHS353FVXAZV`](https://stellar.expert/explorer/public/contract/CACMENFFJPJMSDAJQLX4R7K3SFZIW2LJSE3R2UMLGSWHFHS353FVXAZV) | | `CctpForwarder` | 27 | [`CBZL2IH7F6BIDAA3WBNXYKIXSATJGMSW7K5P5MJ6STX5RXN47TZJDF5T`](https://stellar.expert/explorer/public/contract/CBZL2IH7F6BIDAA3WBNXYKIXSATJGMSW7K5P5MJ6STX5RXN47TZJDF5T) | ## Testnet contract addresses | Contract | [Domain](/cctp/concepts/supported-chains-and-domains#domain-identifiers) | Address | | :- | :- | :- | | `TokenMessengerMinter` | 27 | [`CDNG7HXAPBWICI2E3AUBP3YZWZELJLYSB6F5CC7WLDTLTHVM74SLRTHP`](https://stellar.expert/explorer/testnet/contract/CDNG7HXAPBWICI2E3AUBP3YZWZELJLYSB6F5CC7WLDTLTHVM74SLRTHP) | | `MessageTransmitter` | 27 | [`CBJ6MTCKKZG73PMDZCJMSFRD7DQEMI4FKDH7CGDSV4W6FHCRBCQAVVJY`](https://stellar.expert/explorer/testnet/contract/CBJ6MTCKKZG73PMDZCJMSFRD7DQEMI4FKDH7CGDSV4W6FHCRBCQAVVJY) | | `CctpForwarder` | 27 | [`CA66Q2WFBND6V4UEB7RD4SAXSVIWMD6RA4X3U32ELVFGXV5PJK4T4VSZ`](https://stellar.expert/explorer/testnet/contract/CA66Q2WFBND6V4UEB7RD4SAXSVIWMD6RA4X3U32ELVFGXV5PJK4T4VSZ) | ## CCTP interface * `TokenMessengerMinter`: initiates crosschain burns and mints tokens upon attested message receipt. * `MessageTransmitter`: emits messages, verifies attestations, and routes verified messages to the recipient contract. * `CctpForwarder`: completes mint and forward in one transaction when hook data supplies a `forwardRecipient` `strkey`. ### TokenMessengerMinter interface The `TokenMessengerMinter` contract consolidates the roles of both `TokenMessengerV2` and `TokenMinterV2` found on EVM chains. It handles USDC burns, message emission, and token minting once crosschain messages are attested by Circle's Iris service. On Stellar it assumes `mintRecipient` is a contract. Account recipients use `CctpForwarder` and hook-qualified `forwardRecipient` bytes. | Function | Description | Notes | | :- | :- | :- | | `deposit_for_burn` | Burns USDC and emits a crosschain message for minting on another domain. | Standard CCTP transfer initiation. | | `deposit_for_burn_with_hook` | Same as `deposit_for_burn`, but attaches custom metadata (`hook_data`). | Used for programmable transfers and Stellar forwarding. | | `handle_receive_finalized_message` | Mints USDC upon receiving a fully finalized message. | Called by `MessageTransmitter`. | | `handle_receive_unfinalized_message` | Processes partially finalized ("Fast Burn") messages. | Enables faster crosschain transfers. | | `message_body_version` | Returns supported message format version. | Used for compatibility checks. | | `local_message_transmitter` | Returns the linked `MessageTransmitter` address. | Must match configured domain transmitter. | ### MessageTransmitter interface The `MessageTransmitter` contract provides the core messaging layer for CCTP on Stellar. It is responsible for emitting, receiving, and validating crosschain messages, enforcing attestation rules, and ensuring message uniqueness. | Function | Description | Notes | | :- | :- | :- | | `send_message` | Sends a crosschain message with specified domain, recipient, and message body. | Core function for outgoing CCTP messages. | | `receive_message` | Validates a message and its attestation; delivers message body to the recipient. | Called by an offchain forwarding service (or by `CctpForwarder` in the forwarder flow) with an attestation from Circle. | | `get_max_message_body_size` | Returns the maximum allowed message size. | Used by offchain components for validation. | | `is_nonce_used` | Checks if a message nonce has been processed already. | Prevents message replay. | | `get_local_domain` | Returns this contract's domain ID. | Expected to be 27 for Stellar. | | `get_version` | Returns protocol version supported by this transmitter. | Used by Iris attestation service. | ### CctpForwarder interface The `CctpForwarder` contract calls `receive_message` on `MessageTransmitter`, takes the mint, and transfers USDC to `forwardRecipient` parsed from `hook_data`. See [Hook format](/cctp/references/stellar#hook-format) for details. | Function | Description | Notes | | :- | :- | :- | | `mint_and_forward(message: Bytes, attestation: Bytes)` | Verifies message and attestation. Runs `receive_message` so USDC mints to `CctpForwarder`. Sends USDC to `forwardRecipient` from hooks. | Atomic, any failure reverts. | The `CctpForwarder` flow is non-custodial. `mint_and_forward` mints to this contract and pays `forwardRecipient` in one atomic Soroban invocation. Circle does not take custody of the minted balance in between.