# FastX402 JSON Query (JMESPath)

> FastX402 JSON Query (JMESPath) is a paid API for AI agents from fastx402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-27).

Query and reshape a JSON document using a JMESPath expression to extract fields, filter arrays, or project lists.

## Facts

- Endpoint: GET https://fastx402.tools/json-query?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-27
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastx402-json-query-jmespath-18e40b63
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_azdMM5yAJx3ztQIrcN_BB

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 fastx402-json-query-jmespath-18e40b63
```

Example prompt: Take this JSON API response and run the JMESPath expression `tools[?price < \`0.002\`].name` on it to get back just the names of the cheap tools.

## When to prefer this

Use this endpoint when you need to slice, filter, or reshape a JSON document using JMESPath syntax — especially after receiving a large API response and wanting to extract only the relevant fields without writing custom parsing code. It is ideal for agents already familiar with AWS CLI-style queries or when the target data structure is nested and complex.

## Known failure modes

- Invalid JMESPath expression causes a parse or evaluation error
- Malformed JSON input causes a parse failure
- Expression matches nothing, returning null or empty array
- Very large JSON documents may hit size limits or time out
- Missing required `json` or `expression` query parameters returns a 400-style error

## How this service works

200 pay-per-call tools for AI agents, from $0.001 per request in USDC on Base or Solana with x402. No account, no API key.

## Output

Returns a JSON object containing the evaluated `result` (which may be an array, object, string, number, or null depending on the JMESPath expression) and the `expression` that was applied.

## 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": [
      "json",
      "expression"
     ],
     "properties": {
      "json": {
       "type": "string",
       "description": "JSON document"
      },
      "expression": {
       "type": "string",
       "description": "JMESPath expression, e.g. tools[?price < `0.002`].name"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "result": {
       "type": "array",
       "items": {
        "type": "string"
       }
      },
      "expression": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": [
   "dns",
   "qr-code"
  ],
  "expression": "tools[?price < `0.005`].name"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastx402-json-query-jmespath-18e40b63/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fastx402.tools](https://www.zero.xyz/host/fastx402.tools/llms.txt)