JSON diff

Deep-compare two JSON values. Returns a list of changed/added/removed paths (capped at 1000 differences).

Input

Field	Type	Description
a *	any	First JSON value
b *	any	Second JSON value

Example output

{
  "equal": false,
  "differences": [
    {
      "path": "y",
      "type": "changed",
      "a": 2,
      "b": 3
    },
    {
      "path": "z",
      "type": "added",
      "b": 4
    }
  ]
}

Try it - see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/json-diff \
  -H "Content-Type: application/json" \
  -d '{"a":{"x":1,"y":2},"b":{"x":1,"y":3,"z":4}}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/json-diff", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "a": {
      "x": 1,
      "y": 2
    },
    "b": {
      "x": 1,
      "y": 3,
      "z": 4
    }
  }),
});

No wallet? Pay with compute

This is a pure-CPU tool, so an agent without a wallet can pay with proof-of-work instead of USDC: fetch a challenge, solve the sha256 puzzle (16 leading zero bits - a fraction of a second of CPU, no money, no AI tokens), and resend with the X-Pow-Solution header.

import { createHash } from "node:crypto";
const lz = (b) => { let t = 0; for (const x of b) { if (!x) { t += 8; continue; } t += Math.clz32(x) - 24; break; } return t; };
const c = await (await fetch("https://agent402.tools/api/pow/challenge?slug=json-diff")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/json-diff", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"a":{"x":1,"y":2},"b":{"x":1,"y":3,"z":4}}) });

Part of these workflows

This tool is one step in 2 curated multi-tool workflows - agents can fetch the whole sequence as an MCP prompt or call https://agent402.tools/api/skill-packs/{slug}/prompt.

• Data interchange - Bring data in from any structured format, normalize through JSON as the universal pivot, merge with overrides, audit the diff, flatten for downstream systems, and emit to whatever format the next stage actually consumes - CSV for spreadsheets, YAML for config systems, JSON for everything else. The deterministic universal-format-bridge workflow.
• Schema guard - Contract-test a JSON payload in one call: validate it against your schema, infer the schema the payload actually implies, diff the two to expose drift, and return a normalized pretty-print.

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