# Base Gas Oracle (EIP-1559 Fee Estimator)

> Base Gas Oracle (EIP-1559 Fee Estimator) is a paid API for AI agents from kr-x402-mvp.kgy5612.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-31).

Returns real-time EIP-1559 gas fee tiers (slow/standard/fast), base fee, network congestion score, and estimated transaction cost in ETH and USD for the Base L2 blockchain.

## Facts

- Endpoint: GET https://kr-x402-mvp.kgy5612.workers.dev/crypto/base-gas?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-gas-oracle-eip-1559-fee-estimator-b05d273f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-TJZD1aTSu1A-7alFPabE

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability base-gas-oracle-eip-1559-fee-estimator-b05d273f
```

Example prompt: Check the current Base gas fees and tell me which tier is recommended right now — I need the maxFeePerGas, maxPriorityFeePerGas, and the estimated USD cost for an ERC-20 transfer (65000 gas units).

## When to prefer this

Choose this endpoint when your agent needs real-time, structured EIP-1559 gas fee data specifically for the Base L2 network, including ready-to-sign tx_fields and USD cost estimates. It is ideal for onchain trading bots, DeFi automation agents, or any workflow that must decide whether to submit a transaction now or wait. At $0.001 per call it is extremely cheap for programmatic gas checking. Prefer this over generic Ethereum gas oracles when targeting Base, and over RPC-direct calls when you want pre-computed tiered recommendations with congestion context.

## Known failure modes

- Base RPC unavailable: upstream eth_feeHistory call fails, returns 5xx error
- Payment failure: x402 USDC payment not provided or insufficient, returns 402 Payment Required
- Invalid gas_limit: value outside 21000–30000000 range returns 400 validation error
- Stale data: if Base RPC is slow, updated_at may lag by several blocks
- Network congestion spike: fast-tier fee estimates may be outdated within seconds during high volatility

## How this service works

Base gas oracle for agents sending Base txs: EIP-1559 slow / standard / fast tiers (maxFeePerGas + maxPriorityFeePerGas in gwei and wei hex, from eth_feeHistory 20 blocks p10/p50/p90), base fee, congestion 0-1, recommended_tier, ready-to-sign tx_fields, and est. cost in ETH + USD for your gas_limit (default 21000; use 65000 for an ERC-20 transfer). Cheapest paid call ($0.001).

## Output

A JSON object containing: the current block number, all three EIP-1559 fee tiers (slow/standard/fast) each with maxFeePerGas and maxPriorityFeePerGas in both gwei and wei hex, base_fee_gwei, gas_price_gwei, network congestion score (0–1), the recommended_tier string, ready-to-sign tx_fields (type, gas, maxFeePerGas, maxPriorityFeePerGas in hex), estimated transfer cost in ETH and USD for the requested gas_limit, and a timestamp.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "gas_limit": {
       "type": "integer",
       "maximum": 30000000,
       "minimum": 21000,
       "examples": [
        21000,
        150000
       ],
       "description": "Gas units to price (default 21000)"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "block": 37000000,
  "chain": "base",
  "tiers": {
   "fast": {
    "est_cost_usd": 0.0007,
    "max_fee_gwei": 0.025,
    "max_priority_fee_gwei": 0.01
   },
   "slow": {
    "est_cost_usd": 0.0005,
    "max_fee_gwei": 0.006,
    "max_priority_fee_gwei": 0.001
   },
   "standard": {
    "est_cost_usd": 0.0005,
    "max_fee_gwei": 0.011,
    "max_priority_fee_gwei": 0.001
   }
  },
  "sources": [
   "https://mainnet.base.org"
  ],
  "chain_id": 8453,
  "tx_fields": {
   "gas": "0x5208",
   "type": "0x2",
   "maxFeePerGas": "0xa7d8c0",
   "maxPriorityFeePerGas": "0xf4240"
  },
  "congestion": 0.42,
  "updated_at": "2026-10-29T13:30:00Z",
  "base_fee_gwei": 0.005,
  "gas_price_gwei": 0.006,
  "recommended_tier": "standard",
  "gas_price_wei_hex": "0x5b8d80",
  "est_transfer_cost_eth": 1.26e-7,
  "max_priority_fee_gwei": 0.001,
  "max_priority_fee_wei_hex": "0xf4240"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-gas-oracle-eip-1559-fee-estimator-b05d273f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from kr-x402-mvp.kgy5612.workers.dev](https://www.zero.xyz/host/kr-x402-mvp.kgy5612.workers.dev/llms.txt)