# EVM Fee History — Base Fee & Priority Fee

> EVM Fee History — Base Fee & Priority Fee is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-01).

Returns recent base-fee and priority-fee (tip) history for a specified EVM-compatible blockchain over a configurable number of blocks.

## Facts

- Endpoint: POST https://twin.unykorn.org/evm-fee-history?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evm-fee-history-base-fee-priority-fee-adbb0ea8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bnRszzx7Ol2Qsr6yviapF

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 evm-fee-history-base-fee-priority-fee-adbb0ea8 -d '<json body>'
```

Example prompt: Can you pull the recent base fee and priority fee history for Ethereum over the last 30 blocks so I can see whether gas prices are trending up or down right now?

## When to prefer this

Choose this endpoint when you need structured, recent EVM fee history (both base fees and priority fees) across any of ten major chains in a single authenticated API call. It is ideal for agents that need to make gas-cost decisions, monitor fee volatility, or time transactions optimally. Prefer it over raw RPC calls when you want a unified, multi-chain interface without managing your own node connections or dealing with chain-specific RPC quirks.

## Known failure modes

- Invalid or unsupported chain name returns an error — only the ten listed chains are accepted
- Requesting more blocks than available on the network may return partial data or an error
- Payment failure or insufficient balance results in a 402 response without data
- Network timeout or RPC node outage for the requested chain may return a 5xx error
- Malformed request body (missing required params) returns a validation error

## How this service works

Recent base-fee and priority-fee history — Genesis402 / UnyKorn Operator Network

## Output

A JSON response containing an ok flag, a type field set to 'evm-fee-history', a receipt object with transaction hash, USD amount charged, and receipt ID, plus a generated_at ISO8601 timestamp. The core fee history data (base fees and priority fees per block) is embedded in the response for the requested chain and block count.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "chain": {
     "enum": [
      "ethereum",
      "base",
      "polygon",
      "arbitrum",
      "optimism",
      "bsc",
      "avalanche",
      "gnosis",
      "linea",
      "scroll"
     ],
     "type": "string"
    },
    "blocks": {
     "type": "integer",
     "minimum": 0
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "type": "evm-fee-history",
  "receipt": {
   "tx_hash": "0x<64hex>",
   "amount_usd": 0.004,
   "receipt_id": "g402-<16hex>"
  },
  "generated_at": "<iso8601>"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evm-fee-history-base-fee-priority-fee-adbb0ea8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from twin.unykorn.org](https://www.zero.xyz/host/twin.unykorn.org/llms.txt)