# x402 Gas Oracle — EIP-1559 Fee Estimator (Base + Ethereum + Optimism + Arbitrum + Polygon)

> x402 Gas Oracle — EIP-1559 Fee Estimator (Base + Ethereum + Optimism + Arbitrum + Polygon) is a paid API for AI agents from x402.agentutility.ai, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Reads the latest block on a specified EVM chain, derives EIP-1559 base fee, suggests priority fees for safe-low/standard/fast tiers, computes maxFeePerGas, and converts gas costs to USD for common transaction types.

## Facts

- Endpoint: POST https://x402.agentutility.ai/gas-now-base
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-agentutility-ai-1fbd142b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lCXyfHKwA0S5qZwCd-ZML

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 x402-agentutility-ai-1fbd142b -d '<json body>'
```

Example prompt: What are the current gas fees on Base — give me the safe-low, standard, and fast EIP-1559 tiers and tell me how much a Uniswap swap would cost in USD right now?

## When to prefer this

Use this endpoint when you need real-time EIP-1559 gas estimates on Base, Ethereum, Optimism, Arbitrum, or Polygon — especially when you want USD cost breakdowns for specific transaction types like swaps or NFT mints. Prefer this over Etherscan gas tracker when you need multi-chain coverage in a single API call with USD conversion included.

## Known failure modes

- Unsupported chain name returns an error or empty response
- Chain RPC unavailable causes timeout or error
- Stale block data if chain has reorg or is congested
- Missing or invalid chain parameter returns 400-level error
- USD conversion may be stale if price feed is delayed

## How this service works

Gas oracle / gas price API / EIP-1559 fee estimator / Base + Ethereum + Optimism + Arbitrum + Polygon gas tracker / etherscan-gas alternative / pre-tx cost estimator / USD gas-cost calculator / safe-low + standard + fast tier feed. Reads the chain's latest block, derives the EIP-1559 base fee, suggests priority fees for safe-low / standard / fast tiers, computes the total recommended maxFeePerGas, and converts cost to USD for common tx types (transfer, ERC-20 transfer, Uniswap swap, NFT mint).

## Output

Returns the current EIP-1559 base fee from the latest block, suggested priority fees (tip) for safe-low, standard, and fast tiers, the computed maxFeePerGas for each tier, and USD cost estimates for common transaction types including ETH transfer, ERC-20 transfer, Uniswap swap, and NFT mint.

## Example request

```json
{
 "chain": "base",
 "transactionTypes": [
  "uniswap_swap",
  "token_transfer",
  "contract_deployment"
 ]
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "chain": "base",
  "cost_usd": {
   "nft_mint": 0.006,
   "transfer": 0.0008,
   "uniswap_swap": 0.004,
   "erc20_transfer": 0.0012
  },
  "timestamp": "2026-05-06T22:00:00Z",
  "block_number": 27500000,
  "base_fee_gwei": 0.005,
  "eth_price_usd": 3500,
  "priority_fee_gwei": {
   "fast": 0.002,
   "safe_low": 0.001,
   "standard": 0.001
  },
  "total_recommended_gwei": 0.006
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-agentutility-ai-1fbd142b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.agentutility.ai](https://www.zero.xyz/host/x402.agentutility.ai/llms.txt)