Base OnChain Agent is an open-source framework designed to deploy autonomous AI agents on Ethereum-like blockchains. It connects to blockchain nodes via Web3 and uses OpenAI's GPT models to interpret on-chain events such as token transfers or protocol-specific logs. The agent can process natural language prompts or predefined strategies to decide when to execute transactions, call smart contract functions, or respond to governance proposals. Developers can extend modules for custom event listeners, integrate off-chain data feeds, and manage private keys securely. This solution enables automated DeFi operations like liquidity provisioning, arbitrage trading, and portfolio rebalancing with minimal manual intervention.