# Gas Estimate & Fee Quote API (Multi-Chain EVM)

> Gas Estimate & Fee Quote API (Multi-Chain EVM) is a paid API for AI agents from agents.crowdspark.me, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-31).

Estimates gas units and returns slow/standard/fast fee tiers with USD cost for a transaction on Base, Ethereum, Optimism, Arbitrum, or Polygon — including L1 data fees for OP-stack chains and revert detection.

## Facts

- Endpoint: GET https://agents.crowdspark.me/v1/chain/gas?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gas-estimate-fee-quote-api-multi-chain-evm-8b3d156b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fntN0kAibWYnn_aACAyIK

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 gas-estimate-fee-quote-api-multi-chain-evm-8b3d156b
```

Example prompt: Before I sign this transaction, estimate the gas cost on Base — I'm calling contract 0xAbC...123 from 0xDef...456 with this calldata 0xa9059cbb... and value 0 — give me the slow, standard, and fast fee options in ETH and USD.

## When to prefer this

Use this endpoint when you need a pre-flight gas estimate before signing or broadcasting any EVM transaction, especially when you want slow/standard/fast tier breakdown in both native coin and USD. It is particularly valuable for OP-stack chains (Optimism, Base) where L1 data fees add non-trivial cost. Prefer this over raw RPC calls when you need revert detection combined with fee estimation in a single call, or when budgeting agent-driven on-chain operations across multiple EVM chains.

## Known failure modes

- Invalid or unsupported chain name returns an error (valid values: base, ethereum, optimism, arbitrum, polygon)
- Malformed calldata or address may return a revert simulation result with reverted: true rather than an HTTP error
- Missing required parameters defaults to plain native transfer estimate on Base, which may not reflect actual transaction complexity
- Network RPC unavailability for the requested chain may cause timeout or upstream error
- Value expressed in non-wei units (e.g. ETH instead of wei) will produce incorrect gas estimates
- Chainlink price feed outage may affect USD cost calculations

## How this service works

Pay-per-call utilities for AI agents over x402, USDC on Base.

## Output

A JSON object containing: estimated gas units, current base fee in gwei, an array of fee tiers (slow/standard/fast) each with max_fee_per_gas_gwei, max_priority_fee_gwei, est_cost_native, and est_cost_usd; plus chain metadata (chain, chain_id, native token symbol), current ETH/USD price from Chainlink, L1 data fee (for OP-stack chains), block number, and a reverted boolean flag indicating whether the simulated transaction would revert.

## 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",
     "required": [],
     "properties": {
      "to": {
       "type": "string",
       "description": "Optional. Target address; omit for a plain native transfer quote"
      },
      "data": {
       "type": "string",
       "description": "Optional. 0x calldata"
      },
      "from": {
       "type": "string",
       "description": "Optional. Sender address"
      },
      "chain": {
       "enum": [
        "base",
        "ethereum",
        "optimism",
        "arbitrum",
        "polygon"
       ],
       "type": "string",
       "description": "Chain, default base"
      },
      "value": {
       "type": "string",
       "description": "Optional. Value in wei"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "fees": [
   {
    "tier": "slow",
    "est_cost_usd": 0.000541,
    "est_cost_native": "0.000000232928187839",
    "max_fee_per_gas_gwei": "0.01011",
    "max_priority_fee_gwei": "0.00011"
   },
   {
    "tier": "standard",
    "est_cost_usd": 0.00065
   },
   {
    "tier": "fast",
    "est_cost_usd": 0.00211
   }
  ],
  "block": 53115830,
  "chain": "base",
  "method": "eth_estimateGas",
  "native": "ETH",
  "chain_id": 8453,
  "reverted": false,
  "gas_units": "45415",
  "native_usd": 2320.97,
  "base_fee_gwei": "0.005",
  "l1_data_fee_native": "0.000000000857537839"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gas-estimate-fee-quote-api-multi-chain-evm-8b3d156b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agents.crowdspark.me](https://www.zero.xyz/host/agents.crowdspark.me/llms.txt)