# PreFlight Gas Price Check

> PreFlight Gas Price Check is a paid API for AI agents from meryol-agenticmarket-x402.hf.space, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-10).

Returns current gas prices, base fee, priority fee percentiles, ETH price, and estimated transaction costs for a specified EVM chain in real time.

## Facts

- Endpoint: GET https://meryol-agenticmarket-x402.hf.space/gas/now/%7Bchain%7D
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/preflight-gas-price-check-eba1ea43
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_CqAYacqJbsNNCxvSZ9WWo

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 preflight-gas-price-check-eba1ea43
```

Example prompt: Before I sign this swap, check the current gas prices on Base — tell me the base fee, median priority fee, and roughly how much a swap would cost in USD right now.

## When to prefer this

Use this endpoint when an autonomous agent needs to sanity-check gas costs and ETH price on a specific EVM chain (Ethereum, Base, Arbitrum, Optimism) before signing or submitting a transaction. Ideal for pre-trade workflows where you need real-time base fee, priority fee percentiles, and USD-denominated cost estimates for swaps or transfers in a single call.

## Known failure modes

- Unsupported chain identifier returns an error or empty response
- Chain temporarily unavailable or RPC node down returns 5xx
- Stale gas data if the underlying oracle is lagging
- Payment not accepted (x402 payment required) if USDC not provided
- Rate limiting if called too frequently without valid payment

## How this service works

Pre-trade & pre-sign checks for autonomous agents: everything an agent verifies BEFORE signing a transaction — token due diligence, calldata red-flag decoding, oracle freshness, holder concentration, bridge routing with executable calldata, cross-venue perp funding, gas and price sanity checks. EVM chains: Ethereum, Base, Arbitrum, Optimism.

## Output

A JSON object containing the chain name, current base fee in gwei, p50 and p90 priority fees in gwei, current ETH price in USD, estimated USD costs for common transaction types (swap, ETH transfer, ERC-20 transfer), and qualitative gas notes like 'very_cheap_gas'.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "chain": "base",
  "notes": [
   "very_cheap_gas"
  ],
  "cost_usd": {
   "swap": 0.00022,
   "transfer": 0.000026,
   "erc20_transfer": 0.00008
  },
  "base_fee_gwei": 0.003,
  "eth_price_usd": 3120,
  "priority_fee_p50_gwei": 0.001,
  "priority_fee_p90_gwei": 0.002
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/preflight-gas-price-check-eba1ea43/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from meryol-agenticmarket-x402.hf.space](https://www.zero.xyz/host/meryol-agenticmarket-x402.hf.space/llms.txt)