JSON schema from example API: infer a JSON Schema

$0.01 per call · failed calls are never charged · no account or API key needed

Infer a JSON Schema (draft 2020-12) from an example JSON value: types, nested object properties, required keys, array item shapes merged across all items, and string formats (date-time, date, email, uri, uuid). Use to document an API response or to validate later data against the same shape.

When to use it

Turn an example API response into a JSON Schema (draft 2020-12)
Merge the shapes of all items in an array, with optional keys left out of required
Detect string formats such as date-time, email, uri and uuid

Run it free (25 free calls) Buy credits by card (from $5) Example result (JSON)

Inputs

Name	Type	Description
`json` (required)	string	The example JSON

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://agent-data-tools.revmesh2074.workers.dev/json/schema?json=%7B%22id%22%3A1%2C%22email%22%3A%22ada%40example.com%22%2C%22tags%22%3A%5B%22a%22%2C%22b%22%5D%2C%22created%22%3A%222026-10-23T08%3A00%3A00Z%22%7D"

Or one of your 25 free calls, no key:

curl "https://agent-data-tools.revmesh2074.workers.dev/json/schema?json=%7B%22id%22%3A1%2C%22email%22%3A%22ada%40example.com%22%2C%22tags%22%3A%5B%22a%22%2C%22b%22%5D%2C%22created%22%3A%222026-10-23T08%3A00%3A00Z%22%7D&trial=1"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.

Example result

{
  "schema": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "id": {
        "type": "integer"
      },
      "email": {
        "type": "string",
        "format": "email"
      },
      "tags": {
        "type": "array",
        "items": {
          "type": "string"
        }
      },
      "created": {
        "type": "string",
        "format": "date-time"
      }
    },
    "required": [
      "id",
      "email",
      "tags",
      "created"
    ]
  }
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is json_schema, and the first 25 successful calls are free:

https://agent-data-tools.revmesh2074.workers.dev/mcp

Questions

Which JSON Schema version?

Draft 2020-12.

How are mixed numbers handled?

Integers and decimals in the same field widen to number.

How do I pay?

Each successful call costs $0.01; failed calls are not charged. The first 25 calls are free. Then pay with card credits (from $5) or per call in USDC over x402 or MPP. No account or API key is needed.