Date Math

Exact date and time math for AI agents, paid per call. LLMs are unreliable at business days, DST, recurring schedules and holiday calendars. Date Math gives them deterministic answers over HTTP or MCP.

• Price: $0.001 per call in USDC on Base, via x402

• Access: no signup, no API keys

• Base URL: https://date-math.datemath.workers.dev

• MCP endpoint: https://date-math.datemath.workers.dev/mcp (Streamable HTTP)

• Docs for agents: /llms.txt · /openapi.json

Tools

Every response is a JSON object. Errors look like {"error":{"code","message"}}. Full schemas and examples are in /openapi.json.

Related MCP server: bizdays

Examples

# Unpaid call → HTTP 402 with payment terms in the PAYMENT-REQUIRED header
curl -i -X POST https://date-math.datemath.workers.dev/v1/business_hours \
  -H "Content-Type: application/json" \
  -d '{"start":"2026-11-06T16:00","hours":2,"timezone":"Asia/Manila","country":"PH"}'

Paying from code

Any x402 client pays automatically. With the official TypeScript client:

import { wrapFetchWithPaymentFromConfig } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";

const pay = wrapFetchWithPaymentFromConfig(fetch, {
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(privateKeyToAccount(process.env.KEY as `0x${string}`)) }],
});

const res = await pay("https://date-math.datemath.workers.dev/v1/city", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ cities: ["Cebu", "London"] }),
});
console.log(await res.json());

The wallet needs USDC on Base. No ETH is required, because the facilitator pays gas.

Using it over MCP

• Endpoint: https://date-math.datemath.workers.dev/mcp (Streamable HTTP, stateless)

• Listing tools (tools/list) is free.

• Each tool call costs $0.001 via x402 MCP. Payment travels in the tool call's _meta, and x402-aware clients handle it automatically:

import { createx402MCPClient } from "@x402/mcp";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";

const client = createx402MCPClient({
  name: "my-agent", version: "1.0.0",
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }],
  autoPayment: true,
});
await client.connect(new StreamableHTTPClientTransport(new URL("https://date-math.datemath.workers.dev/mcp")));
const r = await client.callTool("public_holidays", { country: "US", year: 2026 });

MCP clients without x402 support can list the tools, but calls return "Payment required".

Run your own copy

The service is a single Cloudflare Worker and fits the free plan: every tool uses 0–6 ms of CPU per call.

cd worker
npm install
npm test                 # 99 tests
npx wrangler login
npx wrangler deploy

Set your own wallet and price in worker/wrangler.toml:

Optional secrets (set with npx wrangler secret put):

• CDP_API_KEY_ID, CDP_API_KEY_SECRET: settle through Coinbase's facilitator first.

• POCKET_PREFIX: a private, unpaid path for trusted relays.

To check your deployment against x402scan's discovery rules, run node tools/x402scan-audit.mjs https://your-worker.workers.dev.

How it's built

• Stack: Hono on Cloudflare Workers, plus @x402/hono and @x402/mcp.

• Discovery: OpenAPI with x-payment-info, /.well-known/x402, x402 Bazaar metadata on every 402, and llms.txt.

• Precomputed data: the holiday and city tables are built at build time (worker/scripts/build-*.mjs), so lookups are O(1) per request.

• Time zones: UTC offsets come from cached Intl formatters and a week-segment cache. They're tested against direct lookups for tricky zones (Morocco, Lord Howe, Chatham).

• Cron: a built-in engine (worker/src/cron.ts), checked against cron-parser on 400 random expressions.

• Workers-specific shim: x402's Bazaar route validator uses Ajv code generation (new Function), which Workers blocks. wrangler.toml aliases it to a no-op shim (worker/src/shims/bazaar.ts).

Data and license

• Code: MIT, see LICENSE.

• Holiday data: derived from date-holidays (CC BY 3.0). Lunar or government-proclaimed dates are rule-based estimates.

• City data: derived from city-timezones (MIT), based on Natural Earth (public domain).

Contact: see info.contact in /openapi.json.