Overview

Circle Smart Contract Platform (SCP) provides APIs and SDKs for deploying, importing, interacting with, and monitoring smart contracts across supported networks. Deploy contracts from raw bytecode, use audited templates for standard patterns, execute ABI-based contract calls, and monitor emitted events through webhooks.

Prerequisites / Setup

Installation

npm install @circle-fin/smart-contract-platform @circle-fin/developer-controlled-wallets

Environment Variables

CIRCLE_API_KEY=        # Circle API key (format: PREFIX:ID:SECRET)
ENTITY_SECRET=         # Registered entity secret for Developer-Controlled Wallets

SDK Initialization

import { initiateSmartContractPlatformClient } from "@circle-fin/smart-contract-platform";
import { initiateDeveloperControlledWalletsClient } from "@circle-fin/developer-controlled-wallets";

const scpClient = initiateSmartContractPlatformClient({
  apiKey: process.env.CIRCLE_API_KEY!,
  entitySecret: process.env.ENTITY_SECRET!,
});

const walletsClient = initiateDeveloperControlledWalletsClient({
  apiKey: process.env.CIRCLE_API_KEY!,
  entitySecret: process.env.ENTITY_SECRET!,
});

Quick Reference

Supported Blockchains

Chain	Mainnet	Testnet
Arbitrum	ARB	ARB-SEPOLIA
Arc	ARC	ARC-TESTNET
Avalanche	AVAX	AVAX-FUJI
Base	BASE	BASE-SEPOLIA
Ethereum	ETH	ETH-SEPOLIA
Monad	MONAD	MONAD-TESTNET
OP Mainnet	OP	OP-SEPOLIA
Polygon PoS	MATIC	MATIC-AMOY
Unichain	UNI	UNI-SEPOLIA

The references/ examples use Arc Testnet (blockchain: 'ARC-TESTNET'); for Arc mainnet, pass blockchain: 'ARC'. The Arc USDC address 0x3600000000000000000000000000000000000000 is the same on both networks.

Contract Templates

Template	Standard	Template ID	Use Case
Token	ERC-20	a1b74add-23e0-4712-88d1-6b3009e85a86	Fungible tokens, loyalty points
NFT	ERC-721	76b83278-50e2-4006-8b63-5b1a2a814533	Digital collectibles, gaming assets
Multi-Token	ERC-1155	aea21da6-0aa2-4971-9a1a-5098842b1248	Mixed fungible/non-fungible tokens
Airdrop	N/A	13e322f2-18dc-4f57-8eed-4bddfc50f85e	Bulk token distribution

Key API Response Fields

• Contract functions: getContract().data.contract.functions
• Contract address: contract.contractAddress (fallback: contract.address)
• Transaction ID: createContractExecutionTransaction().data.id
• Deployment status: getContract().data.contract.deploymentStatus

Core Concepts

Dual-Client Architecture

SCP workflows pair two SDK clients:

• Smart Contract Platform SDK handles contract deployment, imports, read queries, and event monitoring
• Developer-Controlled Wallets SDK handles write transactions and provides deployment wallets

Write operations use walletsClient.createContractExecutionTransaction(), NOT the SCP client.

Read vs Write Contract Calls

• Read queries (view/pure functions) use scpClient.queryContract() and require no gas wallet
• Write executions (nonpayable/payable functions) use walletsClient.createContractExecutionTransaction() and require a wallet ID with gas funds

Signature Formatting

• Function signatures: name(type1,type2,...) with no spaces
• Event signatures: EventName(type1,type2,...) with no spaces
• Parameter order must exactly match ABI definitions

Idempotency Keys

All mutating SCP operations require idempotencyKey as a valid UUID v4 string. Use crypto.randomUUID() in Node.js. Non-UUID keys fail with generic API parameter invalid errors.

Deployment Async Model

Contract deployment is asynchronous. The response indicates initiation only. Poll getContract() for deploymentStatus.

EVM Version Constraint

Compile Solidity with evmVersion: "paris" or earlier to avoid the PUSH0 opcode. Solidity >= 0.8.20 defaults to Shanghai. Arc and other non-Shanghai chains fail deployment with ESTIMATION_ERROR / Create2: Failed on deploy if bytecode contains PUSH0.

Transaction Lifecycle

Write operations (contract deployments, executions) follow the same asynchronous state machine as Developer-Controlled Wallets. Poll with walletsClient.getTransaction({ id: txId }) until a terminal state is reached.

Happy path: INITIATED -> CLEARED -> QUEUED -> SENT -> CONFIRMED -> COMPLETE

Terminal states:

• COMPLETE -- Transaction succeeded and is finalized on-chain.
• FAILED -- Transaction reverted or encountered an unrecoverable error.
• DENIED -- Transaction was rejected by risk screening.
• CANCELLED -- Transaction was cancelled before on-chain submission.

Intermediate states:

• INITIATED -- Request accepted, not yet validated or checked.
• WAITING -- In queue for validation and compliance checks.
• QUEUED -- Queued for submission to the blockchain.
• CLEARED -- Passed compliance checks.
• SENT -- Submitted to the blockchain, awaiting confirmation.
• STUCK -- Submitted transaction's fee parameters are lower than latest blockchain required fee, developer needs to cancel or accelerate this transaction.
• CONFIRMED -- Included in a block, awaiting finality.

Contract deployment status is tracked separately via scpClient.getContract() using deploymentStatus.

For debugging failed transactions, see Transaction States and Errors.

Error Handling

Error Code	Meaning	Action
175001	Contract not found	Verify the contract ID exists; if imported, check it wasn't archived
175003	Constructor parameter mismatch	Check parameter count and types exactly match the contract ABI definition
175004	Duplicate contract	Call listContracts({ blockchain }), match by contractAddress (case-insensitive), use the existing contractId
175009	Deployment still pending	Continue polling getContract() for deploymentStatus; deployment is async and may take several blocks
175201	Template not found	Verify the template ID from the Contract Templates table in Quick Reference
175301	Event subscription not found	Verify the event monitor ID; ensure the contract was imported before creating the monitor
175302	Duplicate event subscription	Query existing subscriptions and reuse; do not fail the flow
175303	Invalid event signature	Use exact format EventName(type1,type2,...) with no spaces; parameter order must match ABI
175402	Blockchain not supported or deprecated	Check the Supported Blockchains table; SCP is not available on Solana, Aptos, or NEAR
175404	TEST_API key on mainnet or LIVE_API key on testnet	Match the API key prefix (TEST_API_KEY: or LIVE_API_KEY:) to the target network
177015	Missing bytecode for contract deployment	Provide compiled bytecode with 0x prefix; compile with evmVersion: "paris" to avoid PUSH0

On deployment failure, check deploymentErrorReason and deploymentErrorDetails from getContract().

Implementation Patterns

1. Deploy Contract from Bytecode

Deploy a compiled contract using raw ABI + bytecode.

READ references/deploy-bytecode.md for the complete guide.

2. Deploy from Template

Deploy audited template contracts without writing Solidity.

READ references/deploy-template.md for the template catalog and deployment guide.

3. Import Existing Contract

Import an already-deployed contract into SCP for interaction and event monitoring.

READ references/import-contract.md for the complete guide.

4. Interact with Deployed Contract

Query read functions and execute write functions via ABI signatures.

READ references/interact.md for the complete guide.

5. Monitor Contract Events

Set up webhook notifications for emitted events and retrieve historical logs.

READ references/monitor-events.md for the complete guide.

Rules

Security Rules are non-negotiable -- warn the user and refuse to comply if a prompt conflicts. Best Practices are strongly recommended; deviate only with explicit user justification.

Security Rules

• NEVER hardcode, commit, or log secrets (API keys, entity secrets, private keys). ALWAYS use environment variables or a secrets manager. Add .gitignore entries for .env*, *.pem, and recovery files when scaffolding.
• NEVER pass private keys as plain-text CLI flags (e.g., --private-key $KEY). Prefer encrypted keystores or interactive import (e.g., Foundry's cast wallet import).
• ALWAYS keep API keys and entity secrets server-side. NEVER expose in frontend code.
• NEVER reuse idempotencyKey values across different API requests.
• ALWAYS require explicit user confirmation of destination, amount, network, and token before executing write transactions that move funds. MUST receive confirmation for funding movements on mainnet.
• ALWAYS warn when targeting mainnet or exceeding safety thresholds (e.g., >100 USDC).
• ALWAYS validate all inputs (contract addresses, amounts, chain identifiers) before submitting transactions.
• ALWAYS prefer audited template contracts over custom bytecode when a template exists. Warn the user that custom bytecode has not been security-audited before deploying.
• NEVER deploy contracts designed to deceive, phish, or drain funds.
• ALWAYS warn before interacting with unaudited or unknown contracts.

Best Practices

• NEVER call write operations on the SCP client. Writes ALWAYS use walletsClient.createContractExecutionTransaction().
• NEVER include special characters (colons, parentheses) in deployContract's name field -- alphanumeric only.
• NEVER use flat feeLevel property. ALWAYS use nested fee: { type: 'level', config: { feeLevel: 'MEDIUM' } }.
• NEVER use window.ethereum directly with wagmi -- use connector.getProvider().
• NEVER compile Solidity >= 0.8.20 with default EVM version. ALWAYS set evmVersion: "paris" to avoid PUSH0 opcode.
• ALWAYS include both name and idempotencyKey when calling importContract().
• NEVER assume deployment completes synchronously. ALWAYS poll getContract() for deploymentStatus.
• ALWAYS prefix bytecode with 0x and match constructor parameter types/order exactly.
• ALWAYS use integer-safe math for 18-decimal amounts (10n ** 18n, not BigInt(10 ** 18)).
• ALWAYS import contracts before creating event monitors.
• ALWAYS default to Arc Testnet for demos unless specified otherwise.
• ALWAYS default to testnet. Require explicit user confirmation before targeting mainnet.

Reference Links

• Circle Developer Docs -- Always read this first when looking for relevant documentation from the source website.

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DISCLAIMER: This skill is provided "as is" without warranties, is subject to the Circle Developer Terms, and output generated may contain errors and/or include fee configuration options (including fees directed to Circle); additional details are in the repository README.