# Public EVM Fee Observation Comparison

> Public EVM Fee Observation Comparison is a paid API for AI agents from market.datapackvibe.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-19).

Fetches and compares timestamped gas fee observations across up to three EVM chains (Base, Arbitrum, Optimism) using free public RPC endpoints.

## Facts

- Endpoint: POST https://market.datapackvibe.com/x402/assistant-local-gas-comparison?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/public-evm-fee-observation-comparison-ddc83f4a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XzaXQjAKUdkvyn0M7mtHD

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 public-evm-fee-observation-comparison-ddc83f4a -d '<json body>'
```

Example prompt: Can you compare the current gas fees on Base, Arbitrum, and Optimism right now and tell me which chain is cheapest?

## When to prefer this

Choose this endpoint when you need a quick, low-cost snapshot comparison of gas fees across Base, Arbitrum, and/or Optimism using public RPC data. Ideal for agents routing transactions to the cheapest chain or logging fee benchmarks. Not suitable when you need total transaction cost including L1 data fees, guaranteed inclusion estimates, or chains beyond these three L2s.

## Known failure modes

- Partial source failure: one or more chains may return incomplete or missing data if the public RPC is unresponsive
- Invalid chain enum: supplying a chain name other than base, arbitrum, or optimism will be rejected
- Exceeding maxItems: requesting more than 3 chains is invalid
- Stale data: public RPC nodes may return slightly lagged fee data
- Payment failure: x402 payment of 0.01 USDC must succeed before data is returned

## How this service works

Public EVM Fee Observation Comparison: Compare timestamped fee observations for up to three supported chains using free public RPC: Base, Arbitrum and Optimism. Includes partial-source failures. Excludes L1 data fees; this is not a total-cost quote or inclusion guarantee. 0.01 USDC includes one bounded crypto-data report.

## Output

Returns timestamped gas fee observations for each requested chain (Base, Arbitrum, Optimism), sourced from free public RPCs. Includes per-chain fee data and flags any partial-source failures. Does not include L1 data fees and is not a total cost quote or transaction inclusion guarantee.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "chains": {
   "type": "array",
   "items": {
    "enum": [
     "base",
     "arbitrum",
     "optimism"
    ],
    "type": "string"
   },
   "default": [
    "base",
    "optimism"
   ],
   "maxItems": 3,
   "minItems": 1,
   "uniqueItems": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/public-evm-fee-observation-comparison-ddc83f4a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from market.datapackvibe.com](https://www.zero.xyz/host/market.datapackvibe.com/llms.txt)