# Base Chain Gas Fee History

> Base Chain Gas Fee History 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 current and historical gas fee estimates for the Base L2 chain, including tiered fee recommendations (slow/standard/fast), congestion level, and EIP-1559 fields.

## Facts

- Endpoint: GET https://kr-x402-mvp.kgy5612.workers.dev/api/chain/fee-history?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-chain-gas-fee-history-988c7d75
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2xQ65y9OwE-599Gf1iQjB

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-chain-gas-fee-history-988c7d75
```

Example prompt: What are the current gas fees on Base right now — give me the standard and fast tiers with estimated USD cost for a basic ETH transfer of 21000 gas units?

## When to prefer this

Choose this endpoint when an AI agent needs real-time Base L2 gas fee data without requiring API key setup — ideal for onchain trading bots, DeFi agents, and wallet automation that pay per call via x402 USDC micropayments. Prefer over free RPCs when structured, tiered fee recommendations with USD cost estimates are needed out of the box.

## Known failure modes

- Upstream Base RPC unavailable — may return stale or error response
- Invalid gas_limit value outside 21000–30000000 range returns 400 validation error
- Payment failure via x402 (insufficient USDC balance) blocks request
- Response may be slightly delayed if Base network is experiencing high load

## How this service works

Pay-per-call crypto microdata for trading/onchain AI agents via x402 (USDC on Base): Base gas, token risk, balances, multi-venue prices, Hyperliquid book/funding, kimchi premium. No API keys.

## Output

Returns a JSON object with current block number, base fee in gwei, gas price in gwei and wei hex, EIP-1559 tx fields (maxFeePerGas, maxPriorityFeePerGas), three fee tiers (slow/standard/fast) each with max_fee_gwei, max_priority_fee_gwei, and est_cost_usd, a congestion score (0-1), a recommended_tier string, estimated ETH transfer cost, sources list, chain_id (8453), and updated_at 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-chain-gas-fee-history-988c7d75/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)