# Saylor Innovations Data Desk – EVM Gas Fee History

> Saylor Innovations Data Desk – EVM Gas Fee History is a paid API for AI agents from saylorinnovations.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-30).

Returns base fee, block fullness, and priority tip percentiles for up to 100 recent blocks across 16 EVM-compatible chains

## Facts

- Endpoint: GET https://saylorinnovations.com/api/chain/fee-history?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/saylor-innovations-data-desk-evm-gas-fee-history-ce9300dd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_f8-BrTYIEgo4-MqInQ4rr

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 saylor-innovations-data-desk-evm-gas-fee-history-ce9300dd
```

Example prompt: What does the gas fee history look like on Arbitrum for the last 50 blocks — give me base fees, block fullness, and the median priority tip for each block.

## When to prefer this

Choose this endpoint when you need per-block granularity of EVM gas fee data across multiple chains without setting up your own RPC connections. It covers 16 chains in one unified API, returns structured gwei values with percentile tips, and includes a plain-language interpretation — making it ideal for AI agents that need to reason about gas costs, time transactions, or compare chains without parsing raw RPC output.

## Known failure modes

- Unknown or unsupported chain name/ID returns an error — use one of the 16 supported chain names or their EIP-155 chain ID
- Blocks value out of range (less than 1 or greater than 100) returns a validation error
- RPC node unavailability for a specific chain may cause a null or partial history response
- Missing required 'chain' query parameter returns a 400-level error

## How this service works

Gas fee history for 16 EVM chains over up to 100 recent blocks: base fee, block fullness and priority tip at chosen percentiles for each block.

## Output

A JSON object containing the chain name, chain ID, number of blocks analyzed, next-block base fee estimate (gwei), average base fee (gwei), and a per-block history array (oldest first) where each entry includes the block number, base fee, gas used ratio, and priority tip at the 10th, 50th, and 90th percentiles. Also includes a plain-language 'note' field summarizing the result and a 'source' field indicating the data origin.

## 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": {
       "type": "string",
       "description": "chain name (ethereum, base, arbitrum, optimism, polygon, bsc, avalanche, gnosis, linea, scroll, mantle, blast, sonic, celo, berachain, unichain) or chain id"
      },
      "blocks": {
       "type": "string",
       "description": "optional number of recent blocks, 1 to 100 (default 20)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "json"
    },
    "example": {
     "type": "object",
     "required": [
      "chain",
      "chain_id",
      "blocks",
      "next_block_base_fee_gwei",
      "avg_base_fee_gwei",
      "history",
      "note",
      "source"
     ],
     "properties": {
      "note": {
       "type": "string",
       "description": "plain-language reading of the result, including units"
      },
      "chain": {
       "type": "string",
       "description": "the chain name that was queried"
      },
      "blocks": {
       "type": "number",
       "description": "blocks in the history"
      },
      "source": {
       "type": "string",
       "description": "where the data was read from"
      },
      "history": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "object",
        "properties": {
         "block": {
          "type": [
           "number",
           "null"
          ],
          "description": "block number"
         },
         "tip_p10_gwei": {
          "type": [
           "number",
           "null"
          ],
          "description": "10th percentile priority tip, gwei"
         },
         "tip_p50_gwei": {
          "type": [
           "number",
           "null"
          ],
          "description": "median priority tip, gwei"
         },
         "tip_p90_gwei": {
          "type": [
           "number",
           "null"
          ],
          "description": "90th percentil
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/saylor-innovations-data-desk-evm-gas-fee-history-ce9300dd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from saylorinnovations.com](https://www.zero.xyz/host/saylorinnovations.com/llms.txt)