Date arithmetic

Add (or subtract) a duration to a date. duration like "2d", "-3h", "1w 2d", "90m". Returns the resulting UTC ISO timestamp.

Input

Field	Type	Description
date	any	Base date (default now)
duration *	string	e.g. "2d", "-3h", "1w"

Example output

{
  "result": "2026-06-13T15:00:00.000Z"
}

Try it - see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/add-time \
  -H "Content-Type: application/json" \
  -d '{"date":"2026-06-11T12:00:00Z","duration":"2d 3h"}'

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/add-time", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "date": "2026-06-11T12:00:00Z",
    "duration": "2d 3h"
  }),
});

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=add-time")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/add-time", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"date":"2026-06-11T12:00:00Z","duration":"2d 3h"}) });

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.

• Meeting scheduler - Schedule a meeting across timezones without the round-tripping. Convert a proposed UTC slot into every attendee's local time, verify it lands on a working day for each, project the end time, generate human-readable countdowns, expand recurring rules, and report exactly how far out the slot sits - in one deterministic pass.
• Multi-stop trip planner - Plan a multi-stop journey deterministically: geocode each stop, sum the pairwise haversine distances, estimate arrival times by adding driving hours per leg, count business days from today to each arrival, and pull the weather forecast at every US stop. Six tools - three pure-CPU (math + time), three egress (geocoding + weather) - covering the deterministic skeleton of every road-trip / sales-tour / delivery-route planning problem.

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