On-Chain Keepers vs Off-Chain Keepers for Harvest Triggers

Execution is trust-minimized: Logic and state changes are verified by the network consensus (e.g., via Chainlink Automation, Gelato Network, or Keep3r Network). This eliminates reliance on a single operator's honesty. This matters for high-value protocols managing >$100M in TVL where the cost of failure is catastrophic.

Every trigger costs gas: Each execution (e.g., a harvest on Aave or Compound) requires paying for on-chain computation and storage. On Ethereum Mainnet, this can range from $5 to $50+ per transaction during congestion. This matters for frequent, low-margin strategies where gas can erode 50%+ of profits.

Sub-cent execution costs: Off-chain servers (e.g., custom AWS Lambda, OpenZeppelin Defender, or private nodes) pay negligible compute fees, enabling sub-second, high-frequency triggers. This matters for arbitrage bots, dynamic rebalancing, or micro-yield optimizations where latency and cost-per-tx are critical.

Single point of failure: Relies on the uptime and honesty of the operator's infrastructure. A server outage or malicious act can cause missed harvests or liquidations. This matters for mission-critical financial operations where SLAs of 99.9%+ uptime are non-negotiable and cannot be externally verified.

Execution Guarantee: Transactions are triggered by a smart contract or permissionless network (e.g., Gelato Network, Chainlink Automation). No single entity can block a harvest. This is critical for trust-minimized protocols where users must be certain strategies execute as coded, regardless of external conditions.

Fixed Fee Model: Services like Keep3r Network or custom Solidity time-locks incur a known, on-chain fee paid in native gas tokens. This allows for precise profitability modeling for vaults, as keeper costs are transparent and baked into the smart contract logic, avoiding surprise operational expenses.

Optimized Execution: Off-chain servers (e.g., OpenZeppelin Defender, custom scripts) can monitor multiple conditions and execute in a single, optimally timed transaction. This reduces gas overhead by 20-40% compared to naive on-chain polling, crucial for high-frequency strategies on Ethereum Mainnet.

Rapid Iteration: Logic changes don't require smart contract redeploys. Teams can quickly update trigger parameters, add data sources (e.g., CoinGecko API), or integrate new protocols. This is ideal for rapidly evolving yield farms or protocols in early-stage product development.

Reliance on Incentives: If keeper rewards are insufficient due to network congestion or low profitability, transactions may not be submitted, causing harvest lags or missed cycles. This introduces a liveness risk that is harder to mitigate than simply restarting a server.

Operational Burden: Requires securing private keys, maintaining server uptime (99.9%+ SLA), and implementing monitoring (e.g., Prometheus, PagerDuty). This creates single points of failure and attack vectors (key leakage) that are unacceptable for protocols valuing maximal decentralization.

Guaranteed Execution: Transactions are submitted by a permissionless network (e.g., Chainlink Automation, Gelato). Success is enforced by economic incentives and slashing, crucial for time-sensitive liquidations. Decentralized & Censorship-Resistant: No single point of failure. Relies on a decentralized oracle network, aligning with DeFi's trust-minimization ethos for protocols like MakerDAO.

Higher Gas Costs & Latency: Every check and execution pays gas. For frequent, low-value harvests on Ethereum mainnet, this can erode profits. Latency is bound by block times (e.g., ~12 sec on Ethereum). Complex Upkeep Registration: Managing upkeep IDs, funding subscriptions (e.g., on Gelato), and monitoring requires DevOps overhead compared to a simple cron job.

Extreme Cost Efficiency & Speed: A cloud function or dedicated server (AWS Lambda, GCP) triggers transactions. Near-zero operational cost vs. gas, and sub-second latency, ideal for high-frequency arbitrage bots or optimizing MEV. Full Control & Flexibility: Custom logic, complex conditional checks, and integration with any API (e.g., CoinGecko for price) are trivial to implement without smart contract limitations.

Centralization Risk & Reliability: A single server or AWS region outage halts all operations. Requires robust DevOps (monitoring, failover) to approach 99.9% uptime. Security & Trust Assumptions: The keeper's private key must be secured off-chain. This creates a hot wallet attack vector, a critical consideration for protocols managing significant TVL.