# Crosschain Gas & Priority Fee Oracle

> Crosschain Gas & Priority Fee Oracle is a paid API for AI agents from api.fadeandco.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-29).

Returns current base fee, next-block projected base fee (EIP-1559), and priority-fee percentiles (p10/p50/p99) for Ethereum, Base, or Arbitrum from live public RPC nodes.

## Facts

- Endpoint: GET https://api.fadeandco.workers.dev/api/agent-intel/crosschain-gas-priority-fee?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/crosschain-gas-priority-fee-oracle-20fa8913
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cFQKuk8-qrnX3KNMAkPMT

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 crosschain-gas-priority-fee-oracle-20fa8913
```

Example prompt: What are the current base fee and priority fee percentiles on Base right now — including the projected next-block base fee?

## When to prefer this

Choose this endpoint when you need real-time EIP-1559 gas data (base fee + tip percentiles) for Ethereum, Base, or Arbitrum and want a single unified interface rather than querying multiple RPC nodes directly. Prefer this over generic gas APIs when you need the next-block base fee projection and multi-block averaged priority fee percentiles together in one call. Not suitable for Solana, multi-block congestion forecasting, or historical gas time-series.

## Known failure modes

- Unsupported chain value returns error (only ethereum, base, arbitrum accepted; Solana not supported)
- Public RPC node unavailability or rate limiting may cause a timeout or stale data
- nextBaseFeeGwei is a single-block projection only, not a multi-block congestion forecast — may not reflect sudden demand spikes
- No authentication errors since it is public RPC-based, but x402 payment failure blocks access

## How this service works

Current base fee and priority-fee percentiles (10th, 50th, 99th) for Ethereum, Base or Arbitrum from public RPC nodes, with the next block's base fee projected from the last block's fullness (EIP-1559 rule). Solana is not included here. Forecasts are a one-block projection, not a congestion model.

## Output

A JSON object containing the chain name, source RPC URL, timestamp (checkedAt), current baseFeeGwei, projected nextBaseFeeGwei (one-block EIP-1559 projection from last block's gas used ratio), priorityFeeGwei percentiles (p10, p50, p99) from the latest block, lastBlockGasUsedRatio, and averagePriorityFeeGweiLast5Blocks (p10, p50, p99).

## 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": {
      "chain": {
       "type": "string",
       "description": "ethereum, base or arbitrum (default ethereum)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "chain": "base",
  "source": "https://base-rpc.publicnode.com",
  "checkedAt": "2026-10-23T09:35:18.792Z",
  "baseFeeGwei": 0.005,
  "nextBaseFeeGwei": 0.004516,
  "priorityFeeGwei": {
   "p10": 0.00001,
   "p50": 0.001,
   "p99": 0.1467
  },
  "lastBlockGasUsedRatio": 0.112419,
  "averagePriorityFeeGweiLast5Blocks": {
   "p10": 0.000353,
   "p50": 0.001,
   "p99": 0.07469
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/crosschain-gas-priority-fee-oracle-20fa8913/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.fadeandco.workers.dev](https://www.zero.xyz/host/api.fadeandco.workers.dev/llms.txt)