# Gas Oracle: Cheapest-Chain Ranking by USD Transaction Cost

> Gas Oracle: Cheapest-Chain Ranking by USD Transaction Cost is a paid API for AI agents from x402.professorsausages.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-09-14).

Returns all supported blockchain networks ranked by all-in USD transaction cost, identifying the cheapest chain and potential savings versus Ethereum.

## Facts

- Endpoint: GET https://x402.professorsausages.com/gas-oracle/compare
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/gas-oracle-cheapest-chain-ranking-by-usd-transaction-cost-762f29aa
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0Xe09suS8AiAo75aE6uj0

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-oracle-cheapest-chain-ranking-by-usd-transaction-cost-762f29aa
```

Example prompt: Which blockchain is the cheapest right now for submitting a transaction? Give me a full ranking of all supported chains by all-in USD cost and tell me how much I'd save compared to Ethereum mainnet.

## When to prefer this

Use this endpoint when you need to compare transaction costs across multiple chains simultaneously to select the most cost-efficient network. Prefer this over the single-chain gas endpoint when the goal is cross-chain optimization or routing decisions rather than fetching bid-ready fee parameters for a specific chain.

## Known failure modes

- Gas oracle data unavailable for one or more chains — those chains appear in the 'degraded' array with reason details
- All chains degraded — ranking may be empty or incomplete
- Payment not received — 402 response requiring x402 USDC micropayment
- Stale data if underlying gas feeds are lagging — check fetchedAt timestamp
- Network timeout from upstream RPC providers

## How this service works

Cheapest-chain ranking: all supported chains by all-in USD tx cost

## Output

Returns a ranked array of all supported chains sorted by all-in USD transaction cost, the name of the cheapest chain, the gas used, transaction speed, transaction type, savings in USD versus Ethereum, a timestamp of when data was fetched, and a list of any degraded (unavailable or stale) chains.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  },
  "output": {
   "type": "object"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/gas-oracle-cheapest-chain-ranking-by-usd-transaction-cost-762f29aa/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.professorsausages.com](https://www.zero.xyz/host/x402.professorsausages.com/llms.txt)