API documentation

Base URL https://bankday.jacklehoff4866.workers.dev/v1. Every endpoint is a GET returning JSON. Dates are YYYY-MM-DD.

Quickstart

1. Get a free API key (instant, 1,000 requests/month).
2. Call an endpoint:

export BANKDAY_KEY=bd_live_...
curl "https://bankday.jacklehoff4866.workers.dev/v1/today?calendar=us-fed" -H "Authorization: Bearer $BANKDAY_KEY"

Authentication

Send your key in the Authorization: Bearer header (preferred) or X-API-Key header. ?api_key= also works for quick tests, but keeps keys in logs, so avoid it in production. Keys can be rotated from the dashboard. CORS is open, but don't ship your key in public front-end code; call Bankday from your server.

Calendars

A calendar is a set of weekend days plus a list of closures. Three kinds:

• Payment rails (when money settles): us-fed US Federal Reserve (FedACH, Fedwire); us-fednow FedNow & RTP (24x7x365); eu-target2 TARGET2 / T2 (Eurosystem); uk-bacs UK Bacs & Faster Payments settlement.
• Exchanges (full-day trading closures), by ISO 10383 MIC: xnys, xnas, xcme, xlon, xtse, xasx, xjpx, xhkg, xshg, xshe and 18 more.
• Countries (national public holidays, local weekends), by ISO 3166 alpha-2 code: us, gb, de, in… 247 countries.

Which one should I use? For US bank transfers, ACH and wires use us-fed, not us: the Fed's schedule differs from federal-government closures. For euro payments use eu-target2. For UK Direct Debits use uk-bacs. For trade settlement use the exchange.

Each calendar has a coverage range (most 2000–2040). Requests outside it return 422 date_out_of_range rather than a wrong answer.

Joint calendars

Pass several ids separated by commas. A day is a business day only if it is a business day on every calendar, and responses list which calendar closed it. Typical uses: cross-border payouts (us-fed,eu-target2), US equities settled in USD (xnys,us-fed), multi-country payroll.

Is a date a business day?

Returns whether date is a business day on the calendar, why not (weekend or the holiday name, per calendar), and the next and previous business days. Alias: /v1/is-business-day.

curl "https://bankday.jacklehoff4866.workers.dev/v1/business-day?calendar=us-fed&date=2026-10-12" \
  -H "Authorization: Bearer $BANKDAY_KEY"

{
  "calendar": "us-fed",
  "date": "2026-10-12",
  "weekday": "Monday",
  "business_day": false,
  "closures": [{ "calendar": "us-fed", "reason": "holiday", "name": "Columbus Day" }],
  "next_business_day": "2026-10-13",
  "previous_business_day": "2026-10-09"
}

Today's status in the calendar's time zone

Same as business-day for the current date in the calendar's local time zone (e.g. America/New_York for us-fed), plus the next five holidays within 120 days.

curl "https://bankday.jacklehoff4866.workers.dev/v1/today?calendar=xnys" \
  -H "Authorization: Bearer $BANKDAY_KEY"

Add or subtract business days

Moves days business days from date. The start date itself is not counted, so adding 1 business day to a Friday gives the following Monday (if it is open). Negative values go backwards.

curl "https://bankday.jacklehoff4866.workers.dev/v1/business-days/add?calendar=us-fed&date=2026-11-25&days=2" \
  -H "Authorization: Bearer $BANKDAY_KEY"

{
  "calendar": "us-fed",
  "date": "2026-11-25",
  "days": 2,
  "result": "2026-11-30",
  "result_status": { "date": "2026-11-30", "weekday": "Monday", "business_day": true, "closures": [] }
}

Count business days between two dates

Counts business days d with start < d ≤ end (the usual "how many business days until"). Pass include_start=true to count start ≤ d ≤ end. Returns a negative number when end is before start.

curl "https://bankday.jacklehoff4866.workers.dev/v1/business-days/count?calendar=gb&start=2026-12-18&end=2027-01-08" \
  -H "Authorization: Bearer $BANKDAY_KEY"

Next (or previous) business day

The first business day strictly after date (default: today in the calendar's time zone). Use inclusive=true to return the date itself when it is a business day. /v1/business-days/previous works the same way backwards.

curl "https://bankday.jacklehoff4866.workers.dev/v1/business-days/next?calendar=eu-target2&date=2026-12-24" \
  -H "Authorization: Bearer $BANKDAY_KEY"

Adjust a date with a business-day convention

Rolls a non-business date using ISDA-style conventions: following, preceding, modified_following (following, unless that crosses into the next month), modified_preceding. Business days are returned unchanged.

curl "https://bankday.jacklehoff4866.workers.dev/v1/business-days/roll?calendar=us-fed&date=2026-05-31&convention=modified_following" \
  -H "Authorization: Bearer $BANKDAY_KEY"

List business days in a range

All business days between start and end inclusive (max 2 years).

curl "https://bankday.jacklehoff4866.workers.dev/v1/business-days?calendar=jp&start=2026-12-25&end=2027-01-10" \
  -H "Authorization: Bearer $BANKDAY_KEY"

List holidays

Holidays for a year (default: current year) or a date range up to 10 years. For joint calendars every calendar's holidays are listed with a calendar field.

curl "https://bankday.jacklehoff4866.workers.dev/v1/holidays?calendar=uk-bacs&year=2027" \
  -H "Authorization: Bearer $BANKDAY_KEY"

FX spot value date

Spot date for a currency pair traded on trade_date. T+2 by default, T+1 for USD/CAD, USD/TRY, USD/RUB, USD/PHP and USD/KZT. The intermediate day only needs to be a business day for the non-USD currency; the spot date must be a business day for both currencies and, for crosses such as EURGBP, also a USD business day. Currencies map to settlement calendars (USD → us-fed, EUR → eu-target2, GBP → uk-bacs, others → country).

curl "https://bankday.jacklehoff4866.workers.dev/v1/fx/spot?pair=EURUSD&trade_date=2026-11-25" \
  -H "Authorization: Bearer $BANKDAY_KEY"

{
  "pair": "EURUSD",
  "trade_date": "2026-11-25",
  "spot_lag": 2,
  "spot_date": "2026-11-27",
  "calendars": { "EUR": "eu-target2", "USD": "us-fed" },
  "convention": "T+2 spot: ..."
}

US ACH settlement estimate

Estimates when an ACH entry settles at the Federal Reserve, given when you submit it. Same Day ACH uses the three FedACH windows (submission deadlines 10:30 a.m., 2:45 p.m. and 4:45 p.m. ET; settlement 1:00, 5:00 and 6:00 p.m. ET) and the $1,000,000 per-payment limit. Standard ACH settles the next settlement day at 8:30 a.m. ET. Your bank's (ODFI's) cut-offs are earlier than the Fed's.

curl "https://bankday.jacklehoff4866.workers.dev/v1/ach/settlement?type=same_day&submitted_at=2026-10-09T17:10:00-04:00" \
  -H "Authorization: Bearer $BANKDAY_KEY"

List calendars

All calendars with metadata (type, weekend days, time zone, coverage years, source). Filter with type and q. GET /v1/calendars/{id} returns one calendar plus this year's holidays.

curl "https://bankday.jacklehoff4866.workers.dev/v1/calendars?type=rail" \
  -H "Authorization: Bearer $BANKDAY_KEY"

Your plan and usage

Plan, usage for the current month and usage history. Not counted toward your quota.

curl "https://bankday.jacklehoff4866.workers.dev/v1/account" \
  -H "Authorization: Bearer $BANKDAY_KEY"

Errors

Errors use standard HTTP status codes and a JSON body:

{ "error": { "code": "date_out_of_range", "message": "...", "supported_years": [2000, 2040] } }

Quotas & response headers

Each response includes x-quota-limit, x-quota-used, x-quota-remaining, x-plan and x-request-id. Free accounts are blocked at the monthly limit; paid plans continue with overage billing. Responses are deterministic for past dates, so cache them freely.

MCP server for AI agents

Bankday exposes a remote Model Context Protocol server at https://bankday.jacklehoff4866.workers.dev/mcp (streamable HTTP). Tools: is_business_day, add_business_days, count_business_days, list_holidays, today_status, fx_spot_date, ach_settlement_date, search_calendars. Each tool call counts as one request.

{
  "mcpServers": {
    "bankday": {
      "type": "http",
      "url": "https://bankday.jacklehoff4866.workers.dev/mcp",
      "headers": { "Authorization": "Bearer bd_live_..." }
    }
  }
}

Claude Code: claude mcp add --transport http bankday https://bankday.jacklehoff4866.workers.dev/mcp --header "Authorization: Bearer bd_live_..."

Code samples

JavaScript / TypeScript

async function bankday(path, params) {
  const url = new URL("https://bankday.jacklehoff4866.workers.dev/v1/" + path);
  Object.entries(params).forEach(([k, v]) => url.searchParams.set(k, v));
  const res = await fetch(url, { headers: { Authorization: `Bearer ${process.env.BANKDAY_KEY}` } });
  if (!res.ok) throw new Error((await res.json()).error.message);
  return res.json();
}

const { result } = await bankday("business-days/add", { calendar: "us-fed", date: "2026-12-23", days: 3 });

Python

import os, requests

def bankday(path, **params):
    r = requests.get(f"https://bankday.jacklehoff4866.workers.dev/v1/{path}", params=params,
                     headers={"Authorization": f"Bearer {os.environ['BANKDAY_KEY']}"}, timeout=10)
    r.raise_for_status()
    return r.json()

print(bankday("business-day", calendar="xnys", date="2026-11-26")["business_day"])  # False

Go

req, _ := http.NewRequest("GET", "https://bankday.jacklehoff4866.workers.dev/v1/fx/spot?pair=EURUSD&trade_date=2026-11-25", nil)
req.Header.Set("Authorization", "Bearer "+os.Getenv("BANKDAY_KEY"))
resp, err := http.DefaultClient.Do(req)

Google Sheets / Excel

=IMPORTDATA("https://bankday.jacklehoff4866.workers.dev/v1/business-days/add?calendar=us-fed&date=2026-12-23&days=3&api_key=YOUR_KEY")