# Blockchain Fee History API

> Blockchain Fee History API is a paid API for AI agents from biosfera.46-62-215-147.sslip.io, paid per call via x402, $0.0015/call, status unknown (last checked 2026-10-01).

Returns recent base fees, gas used ratios, and 25/50/75 percentile priority fee tips (in gwei) for the last N blocks on Base, Ethereum, Arbitrum, Optimism, or Polygon.

## Facts

- Endpoint: GET https://biosfera.46-62-215-147.sslip.io/o/fee-history?utm_source=zero.xyz
- Price: $0.0015/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/blockchain-fee-history-api-359f1de4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_k-LiF23LCcZzN08Xnc2F0

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 blockchain-fee-history-api-359f1de4
```

Example prompt: What have the base fees and priority fee percentiles looked like over the last 5 blocks on Ethereum? I want to know the 25th, 50th, and 75th percentile tips so I can set a good gas price for my transaction.

## When to prefer this

Choose this endpoint when you need historical fee context — multiple blocks of base fee trends and priority fee percentile distributions — rather than just a single current gas price snapshot. It is ideal for fee estimation logic, dynamic tip selection, or analytics dashboards across Base, Ethereum, Arbitrum, Optimism, or Polygon.

## Known failure modes

- Invalid or unsupported chain name returns an error
- blocks parameter out of range (below 1 or above 20) returns a validation error
- RPC node unavailability for the requested chain may cause a timeout or 503 error
- Missing required 'chain' query parameter returns a 400 bad request

## How this service works

Use when you need recent base fees and priority fee percentiles on Base, Ethereum, Arbitrum, Optimism or Polygon to pick a fee: returns the last N blocks (1 to 20) with base fee, gas used ratio and 25/50/75 percentile tips in gwei.

## Output

A list of up to 20 recent blocks, each containing the base fee (in gwei), gas used ratio, and 25th/50th/75th percentile priority fee tips (in gwei), for the requested EVM-compatible chain.

## 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": [
      "chain"
     ],
     "properties": {
      "chain": {
       "enum": [
        "base",
        "ethereum",
        "arbitrum",
        "optimism",
        "polygon"
       ],
       "type": "string"
      },
      "blocks": {
       "type": "integer",
       "maximum": 20,
       "minimum": 1
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/blockchain-fee-history-api-359f1de4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from biosfera.46-62-215-147.sslip.io](https://www.zero.xyz/host/biosfera.46-62-215-147.sslip.io/llms.txt)