Signing APIs

You can use Circle’s API platform’s signing APIs on blockchains where Wallets do not have full blockchain infrastructure support.

Wallets offers key signing capabilities to a broader range of blockchains where there isn’t full blockchain infrastructure support, such as NEAR and other EVM chains. You can leverage Circle’s advanced MPC key management for signing, and integrate with your own node and data service of choice. Circle offers SDKs and APIs to manage user authentication, wallet creation, and signing capabilities that integrate with your blockchain infrastructure.

Developer-controlled wallets support signing on NEAR and other EVM chains. User-controlled wallets support signing on other EVM chains.

See our step-by-step tutorials for how to sign transactions on different blockchains:

• Sign Transactions on Solana
• Sign Transactions on EVM chains
• Sign Transactions on NEAR

Signing endpoints

You can use the following API endpoints for signing capabilities such as sign transaction, sign typed data, or sign message.

• POST /developer/sign/message
• POST /developer/sign/typedData
• POST /developer/sign/transaction
• POST /developer/sign/delegateAction
• POST /user/wallets
• POST /user/sign/message
• POST /user/sign/typedData
• POST /user/sign/transaction

Lazy Deployment on Smart Contract Accounts (SCAs):

Circle’s Smart Contract Accounts (SCAs) use a lazy deployment strategy. This means that the wallet contract is only deployed to the blockchain upon the first transaction.

If you attempt to use signing endpoints such as /sign/message or /sign/typedData before the wallet is deployed, the request will fail with an error. You must ensure that the user performs a first onchain transaction (for example, sending tokens or interacting with a contract) to deploy the wallet before attempting to sign arbitrary messages or typed data.

For unsupported EVM chains, create a wallet with a blockchain value of EVM or EVM-TESTNET for signing. These virtual blockchain parameters are not tied to specific EVM chains. For details, see Sign transactions on EVM chains.

For EVM-TESTNET wallets, you can sign transactions on the blockchains listed in Chain IDs for signing transactions. Once you transition to mainnet, you can use your EVM wallet to sign transactions on any EVM-compatible chains.

Disclaimer

Using the sign transaction endpoints involves critical actions that can impact your assets and transactions.

Signing transactions carries inherent security risks. Malicious actors can trick users into signing what appears to be a legitimate transaction message. This could potentially allow them to gain unauthorized access to your funds. Always ensure that you are signing transactions only from trusted sources and verify the legitimacy of transaction requests before proceeding.

If you have created Wallets on an EVM-compatible chain such as Ethereum, Polygon, Avalanche, or Arbitrum, an EVM wallet created under the same wallet set maps to the same addresses.

In these cases, it is extremely important that you do not use the EVM wallet to sign transactions for existing Wallets on those chains; for example, sign transaction with chainID = 137 signs MATIC transaction.

Your Wallet transactions will be stuck and you are responsible for any resulting consequences.

Programmable Wallet capabilities

The following table shows the difference in Programmable Wallet capabilities offered on fully managed blockchains vs. Near and other blockchains.

Capability Category	Fully managed blockchains	NEAR and other EVM chains
Wallet Features	User authentication Wallet creation Full transaction lifecycle management: - Signing tx or messages - Broadcast - Monitor deposit - Index tx and balances	User authentication Wallet creation Signing tx or messages
Wallet Infrastructure	Developer-controlled wallets User-controlled wallets	Developer-controlled wallets User-controlled wallets (except NEAR)
Circle Contracts Support	Contracts APIs support for most of the chains that PW APIs support (given that the specified chains support smart contracts)	Not supported
Gas Station Support	Access to Gas Station to enable gas sponsorship for all smart contract account wallets Self-serve ability to set up Paymaster policies Available for chains supported by PW that supports smart contract accounts or native gas station for EOA	N/A Supports only EOA wallets. As Gas Station and paymaster policies require the use of SCA Wallets, Gas Station is not supported in this offering.