# Seneschal Cheapest Flashloan Query

> Seneschal Cheapest Flashloan Query is a paid API for AI agents from api.seneschal.space, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Returns the cheapest available flash loan offer across DeFi protocols on Ethereum mainnet

## Facts

- Endpoint: GET https://api.seneschal.space/v1/q/cheapest-flashloan
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/seneschal-cheapest-flashloan-query-65c9a75a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_thGHEqhb7AUTN8oAFMxMz

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 seneschal-cheapest-flashloan-query-65c9a75a
```

Example prompt: What's the cheapest flash loan available on Ethereum mainnet right now — I need to know which protocol to use and what the fee is before I execute an arbitrage trade.

## When to prefer this

Use this endpoint when you need to programmatically find the lowest-cost flash loan on Ethereum mainnet before executing an MEV, arbitrage, or liquidation strategy. Particularly useful when integrated with Seneschal's block builder service, as the data is sourced from mainnet block-building telemetry.

## Known failure modes

- No flash loan liquidity available for requested asset — empty result set
- Malformed properties parameter returns 400 bad request
- Rate limit exceeded returns 402 payment required (x402 USDC on Base)
- Ethereum node connectivity issues may cause stale or unavailable data
- Insufficient x402 USDC balance returns payment error

## How this service works

Single-fact: cheapest flash-loan provider for `asset` on `chain` (default ethereum). Returns {provider, fee_bps, address}.

## Output

Returns data about the cheapest flash loan currently available, including the protocol offering it, the fee rate, and available liquidity for the requested asset parameters.

## Example request

```json
{
 "asset": "ETH"
}
```

## 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": [
      "asset"
     ],
     "properties": {
      "asset": {
       "type": "string",
       "description": "Asset symbol, e.g. WETH, USDC."
      },
      "chain": {
       "type": "string",
       "description": "Chain name (default ethereum)."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asset": {
       "type": "string"
      },
      "chain": {
       "type": "string"
      },
      "found": {
       "type": "boolean"
      },
      "address": {
       "type": "string"
      },
      "fee_bps": {
       "type": "number"
      },
      "provider": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "asset": "WETH",
  "chain": "ethereum",
  "found": true,
  "address": "0xBBBBBbbBBb9cC5e90e3b3Af64bdAF62C37EEFFCb",
  "fee_bps": 0,
  "provider": "morpho-blue"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/seneschal-cheapest-flashloan-query-65c9a75a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.seneschal.space](https://www.zero.xyz/host/api.seneschal.space/llms.txt)