use-developer-controlled-wallets

Overview

Developer-controlled wallets let your application create and manage wallets on behalf of end users, with full custody of private keys secured through an encrypted entity secret. Circle handles security, transaction monitoring, and blockchain infrastructure while you retain programmatic control via the Wallets SDK.

Prerequisites / Setup

Installation

npm install @circle-fin/developer-controlled-wallets

Environment Variables

CIRCLE_API_KEY=      # Circle API key (format: PREFIX:ID:SECRET)
ENTITY_SECRET=       # 32-byte hex entity secret

Entity Secret Registration

The developer must register an entity secret before using the SDK. Direct them to https://developers.circle.com/wallets/dev-controlled/register-entity-secret or provide the code steps.

READ references/register-secret.md for the generation and registration snippets.

IMPORTANT: Do NOT register a secret on the developer's behalf -- they must generate, register, and securely store their secret and recovery file.

SDK Initialization

import { initiateDeveloperControlledWalletsClient } from '@circle-fin/developer-controlled-wallets';

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

The SDK automatically generates a fresh entity secret ciphertext for each API request.

Core Concepts

• Wallet Sets: A group of wallets managed by a single entity secret. Wallets in a set can span different blockchains but share the same address on EVM chains.
• Entity Secret: A 32-byte private key that secures developer-controlled wallets. Generated, encrypted, and registered once. Circle never stores it in plain text.
• Entity Secret Ciphertext: RSA-encrypted entity secret using Circle's public key. Must be unique per API request to prevent replay attacks. The SDK handles this automatically.
• Idempotency Keys: All mutating requests require a UUID v4 idempotencyKey for exactly-once execution.
• Account Types:
  • EOA (Externally Owned Account) -- default choice. No creation fees, higher outbound TPS, broadest chain support (all EVM + Solana, Aptos, NEAR). Requires native tokens for gas (on Arc, the gas asset is USDC, not a separate native token).
  • SCA (Smart Contract Account) -- ERC-4337 compliant. Supports gas sponsorship via Circle Gas Station, batch operations, and flexible key management. EVM-only (not available on Solana, Aptos, NEAR). Avoid on Ethereum mainnet due to high gas costs; prefer on L2s.
• Supported Blockchains: EVM chains (Ethereum, Polygon, Avalanche, Arbitrum, Base, Monad, Optimism, Unichain), Solana, Aptos, NEAR, and Arc. See https://developers.circle.com/wallets/account-types for the latest.