Fee Signal Toolkit

A module that surfaces EIP-1559 fee suggestions and simple historical fee insights from an Ethereum node.

Capabilities

Recommend next-block fee caps

• When the node returns a base fee of 30 gwei for the next block and a priority tip suggestion of 2 gwei, a default target multiplier of 1.2 yields type "eip1559", maxFeePerGas "38000000000", maxPriorityFeePerGas "2000000000", and baseFeePerGas "30000000000". @test
• When the node does not expose base fees but provides a legacy gas price of 15 gwei, the recommendation is type "legacy" with both maxFeePerGas and maxPriorityFeePerGas set to "15000000000". @test

Summarize recent fees

• For a 5-block window with base fees [20, 22, 24, 26, 28] gwei and reward percentiles at the 50th percentile [1, 1.5, 2, 2.5, 3] gwei, it returns baseFeeMedian "24000000000", rewardAtPercentile "2000000000", oldestBlock matching the window start, and newestBlock matching the latest block number. @test

Check priority sufficiency

• Given a node-suggested priority tip of 2 gwei, a candidate of 1 gwei is insufficient (false) and 3 gwei is sufficient (true). @test

Implementation

@generates

API

All fee values are returned as decimal strings representing wei.

export interface FeeRecommendation {
  type: "eip1559" | "legacy";
  maxFeePerGas: string;
  maxPriorityFeePerGas: string;
  baseFeePerGas?: string;
}

export interface FeeWindowSummary {
  baseFeeMedian: string;
  rewardAtPercentile: string;
  oldestBlock: number;
  newestBlock: number;
}

export async function recommendNextBlockFees(targetMultiplier?: number): Promise<FeeRecommendation>;
export async function summarizeRecentFees(blockCount: number, percentile: number): Promise<FeeWindowSummary>;
export async function isPrioritySufficient(candidateTipWei: string): Promise<boolean>;

Dependencies { .dependencies }

web3-eth { .dependency }

Ethereum JSON-RPC client used for fee and gas discovery operations.