JSON to YAML
POST /api/json-to-yamlConvert JSON to YAML. Send POST /api/json-to-yaml with the required field json and pay $0.001 per call over x402 or MPP, or call it free by solving a proof-of-work challenge. It returns a JSON object with yaml.
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
json | any | yes | Any JSON value (or a JSON string of one) Also accepted as data, body, input, obj, object. |
Example request
curl -i -X POST https://agent402.tools/api/json-to-yaml \
-H "Content-Type: application/json" \
-d '{"json":{"name":"Ada","tags":["eng"]}}'
Without payment this returns HTTP 402 Payment Required with the exact price for json-to-yaml; any x402 v2 or MPP client pays it and retries.
Example response
{
"yaml": "name: Ada\ntags:\n - eng\n"
}
| Field | Type | Always present | In the example |
|---|---|---|---|
yaml | string | yes | name: Ada tags: - eng |
From an MCP client
catalog.call {
"slug": "json-to-yaml",
"params": {
"json": {
"name": "Ada",
"tags": [
"eng"
]
}
}
}
On the hosted connector at https://agent402.tools/mcp, catalog.call runs json-to-yaml free (rate-limited, no wallet). Local install: npx -y agent402-mcp.
Errors and behavior
jsonis required. An input the tool rejects returns an HTTP 4xx whose body carrieserror,tool,expected,requiredandexample, so the caller can correct it.- A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement is cancelled when the tool fails. The exception is a Tempo push credential, a transfer the buyer sent before the call: it settles before the tool runs, so if the tool then fails the payment is recorded as a refund owed to the paying wallet.
- Free tier: no outbound network call leaves the server for this tool, so proof-of-work (16 leading zero bits of sha256) pays for it.
- A
GETorHEADto /api/json-to-yaml returns the same 402 quote, so the price can be read without a body. - An
Idempotency-Keyheader makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).
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();
client.setSpendControls?.(false); // keep your own spending ceiling in code
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);
const res = await payFetch("https://agent402.tools/api/json-to-yaml", {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({
"json": {
"name": "Ada",
"tags": [
"eng"
]
}
}),
});
No wallet? Pay with compute
Fetch a challenge, solve the sha256 puzzle (16 leading zero bits, a fraction of a second of CPU), 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-to-yaml")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/json-to-yaml", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"json":{"name":"Ada","tags":["eng"]}}) });
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XML to JSON
POST /api/xml-to-jsonParse XML into a JSON object tree (attributes under _attrs, text under _text; repeated elements become arrays).