UUID v5 (deterministic)

Generate a deterministic name-based UUID (version 5, SHA-1) from a namespace + name - the same inputs always yield the same UUID, for stable IDs without a database. Namespace may be a UUID or an alias: dns | url | oid | x500.

Input

Field	Type	Description
namespace *	string	a UUID, or alias: dns | url | oid | x500
name *	string	the name to hash within the namespace

Example output

{
  "uuid": "0e3f2f0e-... (deterministic)",
  "version": 5
}

Try it - see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/uuid-v5 \
  -H "Content-Type: application/json" \
  -d '{"namespace":"url","name":"https://agent402.tools"}'

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/uuid-v5", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "namespace": "url",
    "name": "https://agent402.tools"
  }),
});

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=uuid-v5")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/uuid-v5", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"namespace":"url","name":"https://agent402.tools"}) });

Part of these workflows

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

• Server-side identity mint - The server-side identity-issuance round-trip: mint a random user-id (UUIDv4), derive a deterministic cross-system correlation-id (UUIDv5), turn the display name into a URL-safe handle, generate a one-time recovery password, hash it for storage, sign a session JWT with HMAC, and base64-encode the recovery bundle for transport. Seven pure-CPU tools - the canonical 'create-user' write path done as one deterministic pipeline.

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