SettleDate API docs

Base URL https://www.elcodev.com/apps/settledate. Every endpoint is a GET that returns JSON. Dates are YYYY-MM-DD; instants are ISO-8601 UTC.

# No key needed for free calendars (60 calls/hour per IP)
curl "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/is-trading-day?date=2026-11-26"

import requests
print(requests.get("https://www.elcodev.com/apps/settledate/v1/markets/XLON/status").json())

console.log(await (await fetch("https://www.elcodev.com/apps/settledate/v1/calendars/US/holidays?year=2027")).json());

Keys and limits

Send your key in the X-API-Key header (or Authorization: Bearer sd_…). Get a free key on the home page. Keyed responses carry X-Usage-Limit and X-Usage-Remaining; keyless responses carry X-RateLimit-Limit and X-RateLimit-Remaining.

Access	Limit	Calendars
No key	60 calls/hour per IP	Free set
Free key	5,000 calls/month	Free set
Starter / Growth / Business	100,000 / 1,000,000 / 5,000,000 calls/month	All

The free set is every country calendar plus XNYS, XNAS, XLON, XETR, XTKS, us-fed, eu-target2, gb-bacs-chaps. Listing endpoints (/v1/calendars, /v1/settlement-cycles, /v1/changes, /v1/usage) are not counted. Failed requests are not counted.

Calendar ids

Exchanges use ISO 10383 MICs: BVMF XAMS XASX XBOM XBRU XCSE XDUB XETR XHEL XHKG XJSE XKRX XLIS XLON XMAD XMEX XMIL XNAS XNYS XNZE XOSL XPAR XSES XSHG XSTO XSWX XTKS XTSE XWBO. Aliases such as NYSE, LSE, XETRA, JPX, HKEX also work.

Payment rails: eu-target2 (Eurosystem T2 / TARGET2 (EUR)), gb-bacs-chaps (UK BACS / CHAPS (England and Wales bank holidays)), us-fed (US Federal Reserve (Fedwire / FedACH)).

Countries use ISO 3166 codes (AE AR AT AU BE BR CA CH CL CN CO CZ …) and some subdivisions: GB-ENG, GB-SCT, GB-NIR, GB-WLS, US-NY, CA-ON, CA-QC, AU-NSW, AU-VIC.

Joint calendars: join up to 8 ids with commas (XNYS,XLON). A day is open only if every calendar is open, and closed responses say which calendar closed it.

Endpoints

GET /v1/calendars

List every calendar with time zone, data range and verification level.

Parameter	Description
`kind`	Optional: exchange, rail or country

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/calendars?kind=exchange"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/calendars",
    params={"kind":"exchange"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/calendars?kind=exchange", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "calendars": [
    {
      "id": "BVMF",
      "kind": "exchange",
      "name": "B3 (Brasil Bolsa Balcao)",
      "country": "BR",
      "currency": "BRL",
      "timezone": "America/Sao_Paulo",
      "data_through": "2030-12-31",
      "verification": {
        "level": "library-derived",
        "checked_against_official": []
      }
    },
    {
      "id": "XAMS",
      "kind": "exchange",
      "name": "Euronext Amsterdam",
      "country": "NL",
      "currency": "EUR",
      "timezone": "Europe/Amsterdam",
      "data_through": "2030-12-31",
      "verification": {
        "level": "library-derived",
        "checked_against_official": []
      }
    }
  ],
  "…": "more"
}

GET /v1/calendars/{id}/is-trading-day

Whether a date is a trading (business) day, and why not. Alias: is-business-day.

Parameter	Description
`date`	Date to check

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/is-trading-day?date=2026-12-25"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/is-trading-day",
    params={"date":"2026-12-25"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/is-trading-day?date=2026-12-25", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "calendar": "XNYS",
  "date": "2026-12-25",
  "weekday": "Fri",
  "is_business_day": false,
  "closed_reasons": [
    {
      "calendar": "XNYS",
      "type": "holiday",
      "name": "Christmas"
    }
  ]
}

GET /v1/calendars/{id}/next-trading-day

The next trading day after date. Alias: next-business-day.

Parameter	Description
`date`	Start date
`inclusive`	true returns `date` itself if it is open

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/next-trading-day?date=2026-12-24"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/next-trading-day",
    params={"date":"2026-12-24"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/next-trading-day?date=2026-12-24", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "calendar": "XNYS",
  "date": "2026-12-24",
  "next_business_day": "2026-12-28",
  "inclusive": false
}

GET /v1/calendars/{id}/previous-trading-day

The trading day before date. Alias: previous-business-day.

Parameter	Description
`date`	Start date
`inclusive`	true returns `date` itself if it is open

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/calendars/XLON/previous-trading-day?date=2026-12-28"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/calendars/XLON/previous-trading-day",
    params={"date":"2026-12-28"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/calendars/XLON/previous-trading-day?date=2026-12-28", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "calendar": "XLON",
  "date": "2026-12-28",
  "previous_business_day": "2026-12-24",
  "inclusive": false
}

GET /v1/calendars/{id}/add-trading-days

Move a date by N trading days; negative N goes back. Alias: add-business-days.

Parameter	Description
`date`	Start date
`n`	Integer between -2000 and 2000

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/calendars/XETR/add-trading-days?date=2026-04-02&n=2"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/calendars/XETR/add-trading-days",
    params={"date":"2026-04-02","n":"2"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/calendars/XETR/add-trading-days?date=2026-04-02&n=2", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "calendar": "XETR",
  "date": "2026-04-02",
  "n": 2,
  "result": "2026-04-08"
}

GET /v1/calendars/{id}/trading-days-between

Count trading days from from (inclusive) to to (exclusive). Negative when to is earlier. Alias: business-days-between.

Parameter	Description
`from`	Start date, inclusive
`to`	End date, exclusive
`inclusive_end`	true counts `to` as well

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS,us-fed/trading-days-between?from=2026-10-01&to=2026-11-01"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS,us-fed/trading-days-between",
    params={"from":"2026-10-01","to":"2026-11-01"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/calendars/XNYS,us-fed/trading-days-between?from=2026-10-01&to=2026-11-01", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "calendars": [
    "XNYS",
    "us-fed"
  ],
  "…": "more"
}

GET /v1/calendars/{id}/holidays

Holidays in a year. Exchange calendars also list early closes and late opens with local times.

Parameter	Description
`year`	4-digit year

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/holidays?year=2026"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/holidays",
    params={"year":"2026"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/calendars/XNYS/holidays?year=2026", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "calendar": "XNYS",
  "year": 2026,
  "holidays": [
    {
      "date": "2026-01-01",
      "name": "New Year's Day",
      "weekday": "Thu"
    },
    {
      "date": "2026-01-19",
      "name": "Dr. Martin Luther King Jr. Day",
      "weekday": "Mon"
    },
    {
      "date": "2026-02-16",
      "name": "President's Day",
      "weekday": "Mon"
    },
    {
      "…": "more"
    }
  ],
  "early_closes": [
    {
      "date": "2026-11-27",
      "close_local": "13:00",
      "weekday": "Fri"
    },
    {
      "date": "2026-12-24",
      "close_local": "13:00",
      "weekday": "Thu"
    }
  ],
  "late_opens": []
}

GET /v1/markets/{mic}/session

Session on a date: open/close (and lunch break) in local time and UTC, and the session type: regular, early_close, late_open or special.

Parameter	Description
`date`	Date

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/markets/XNYS/session?date=2026-11-27"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/markets/XNYS/session",
    params={"date":"2026-11-27"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/markets/XNYS/session?date=2026-11-27", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "market": "XNYS",
  "date": "2026-11-27",
  "open": true,
  "session_type": "early_close",
  "timezone": "America/New_York",
  "local": {
    "open": "09:30",
    "close": "13:00"
  },
  "utc": {
    "open": "2026-11-27T14:30:00Z",
    "close": "2026-11-27T18:00:00Z"
  },
  "regular_close_local": "16:00",
  "utc_offset": "-05:00"
}

GET /v1/markets/{mic}/sessions

Every session in a range, up to 400 days.

Parameter	Description
`from`	Start date
`to`	End date, inclusive

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/markets/XTKS/sessions?from=2026-03-02&to=2026-03-06"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/markets/XTKS/sessions",
    params={"from":"2026-03-02","to":"2026-03-06"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/markets/XTKS/sessions?from=2026-03-02&to=2026-03-06", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "market": "XTKS",
  "from": "2026-03-02",
  "to": "2026-03-06",
  "sessions": [
    {
      "market": "XTKS",
      "date": "2026-03-02",
      "open": true,
      "session_type": "regular",
      "timezone": "Asia/Tokyo",
      "local": {
        "open": "09:00",
        "close": "15:30",
        "break_start": "11:30",
        "break_end": "12:30"
      },
      "utc": {
        "open": "2026-03-02T00:00:00Z",
        "close": "2026-03-02T06:30:00Z",
        "break_start": "2026-03-02T02:30:00Z",
        "break_end": "2026-03-02T03:30:00Z"
      },
      "utc_offset": "+09:00"
    },
    {
      "…": "more"
    }
  ]
}

GET /v1/markets/{mic}/status

Open, closed or lunch break at an instant, with next open and close.

Parameter	Description
`at`	Optional ISO-8601 instant; defaults to now

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/markets/XHKG/status?at=2026-10-26T04:30:00Z"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/markets/XHKG/status",
    params={"at":"2026-10-26T04:30:00Z"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/markets/XHKG/status?at=2026-10-26T04:30:00Z", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "market": "XHKG",
  "at": "2026-10-26T04:30:00Z",
  "local_date": "2026-10-26",
  "local_time": "12:30",
  "timezone": "Asia/Hong_Kong",
  "status": "break",
  "is_open": false,
  "session": {
    "market": "XHKG",
    "date": "2026-10-26",
    "open": true,
    "session_type": "regular",
    "timezone": "Asia/Hong_Kong",
    "local": {
      "open": "09:30",
      "close": "16:00",
      "break_start": "12:00",
      "break_end": "13:00"
    },
    "utc": {
      "open": "2026-10-26T01:30:00Z",
      "close": "2026-10-26T08:00:00Z",
      "break_start": "2026-10-26T04:00:00Z",
      "break_end": "2026-10-26T05:00:00Z"
    },
    "utc_offset": "+08:00"
  },
  "next_open": "2026-10-26T05:00:00Z",
  "next_close": "2026-10-26T08:00:00Z"
}

GET /v1/settlement-date

Settlement date for a trade. The cycle comes from the market's rule for that trade date unless you pass one. Days are counted on the market calendar joined with the settlement-currency calendar (USD → us-fed, EUR → eu-target2, GBP → gb-bacs-chaps).

Parameter	Description
`market`	Exchange MIC
`trade_date`	Trade date (must be a trading day)
`cycle`	Optional override, e.g. T+1
`calendars`	Optional extra calendars to join, comma-separated
`currency_calendar`	Optional override of the cash-leg calendar, or `none`

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/settlement-date?market=XETR&trade_date=2027-10-08"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/settlement-date",
    params={"market":"XETR","trade_date":"2027-10-08"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/settlement-date?market=XETR&trade_date=2027-10-08", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "market": "XETR",
  "trade_date": "2027-10-08",
  "settlement_date": "2027-10-12",
  "cycle": "T+2",
  "basis": "market_rule",
  "status": "in_effect",
  "effective_from": "2014-10-06",
  "rule": "CSDR Art. 5(2) (T+2)",
  "source": "https://eur-lex.europa.eu/eli/reg/2014/909/oj",
  "calendars_used": [
    "XETR",
    "eu-target2"
  ],
  "skipped_days": [],
  "upcoming_change": {
    "cycle": "T+1",
    "effective_from": "2027-10-11",
    "status": "confirmed",
    "rule": "Regulation (EU) 2025/2075 amending CSDR Art. 5(2): T+1 applies from 11 Oct 2027",
    "source": "https://eur-lex.europa.eu/eli/reg/2025/2075/oj"
  }
}

GET /v1/settlement-cycles

Settlement cycle rules by market with status and source.

Parameter	Description
`market`	Optional MIC

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/settlement-cycles?market=XLON"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/settlement-cycles",
    params={"market":"XLON"},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/settlement-cycles?market=XLON", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "settlement_cycles": {
    "XLON": [
      {
        "from": "2014-10-06",
        "days": 2,
        "status": "in_effect",
        "label": "UK CSDR Art. 5(2) (T+2)",
        "source": "https://www.legislation.gov.uk/eur/2014/909/article/5"
      },
      {
        "from": "2027-10-11",
        "days": 1,
        "status": "announced_not_final",
        "label": "HM Treasury: UK T+1 from 11 Oct 2027; draft Central Securities Depositories (Amendment) (Intended Settlement Date) Regulations 2026 published Nov 2025, not yet made (checked 2026-10-24)",
        "source": "https://www.gov.uk/government/publications/accelerated-settlement-t1"
      }
    ]
  },
  "note": "status: in_effect | confirmed (in law, future) | announced_not_final (announced or recommended; legal instrument not final)."
}

GET /v1/usage

Your plan and calls used this month. Requires a key.

curl -H "X-API-Key: $SETTLEDATE_KEY" \
  "https://www.elcodev.com/apps/settledate/v1/usage"

import os, requests

r = requests.get(
    "https://www.elcodev.com/apps/settledate/v1/usage",
    params={},
    headers={"X-API-Key": os.environ["SETTLEDATE_KEY"]},
    timeout=10,
)
r.raise_for_status()
print(r.json())

const res = await fetch("https://www.elcodev.com/apps/settledate/v1/usage", {
  headers: { "X-API-Key": process.env.SETTLEDATE_KEY },
});
if (!res.ok) throw new Error((await res.json()).error.message);
console.log(await res.json());

Example response

{
  "plan": "free",
  "month": "202610",
  "calls_used": 42,
  "monthly_limit": 5000,
  "note": "Counts can lag by a few minutes."
}

GET /v1/changes

The corrections log: every hand override applied on top of the library data, with its official source.

Settlement rules

Status values: in effect the rule applies today; confirmed in law a future change written into law or regulation; announced, not final a future change announced or recommended whose legal instrument isn't final. Responses for trades before a pending change include upcoming_change.

Markets	Cycle	From trade date	Status	Rule
`XNYS` `XNAS`	T+2	2017-09-05	in effect	SEC Rule 15c6-1 (T+2, 2017)
`XNYS` `XNAS`	T+1	2024-05-28	in effect	SEC Rule 15c6-1 amendments (T+1)
`XTSE`	T+2	2017-09-05	in effect	CSA NI 24-101 (T+2)
`XTSE`	T+1	2024-05-27	in effect	CSA NI 24-101 amendments (T+1)
`XMEX`	T+2	2017-09-05	in effect	Indeval (T+2)
`XMEX`	T+1	2024-05-27	in effect	Mexican market move to T+1 (aligned with US/Canada)
`XPAR` `XAMS` `XBRU` `XLIS` `XMIL` `XDUB` `XETR` `XMAD` `XHEL` `XWBO` `XSTO` `XCSE`	T+1	2027-10-11	confirmed in law	Regulation (EU) 2025/2075 amending CSDR Art. 5(2): T+1 applies from 11 Oct 2027
`XOSL`	T+1	2027-10-11	announced, not final	EU T+1 (Reg. 2025/2075) expected to apply in Norway via EEA incorporation; Norwegian implementation not yet final
`XLON`	T+1	2027-10-11	announced, not final	HM Treasury: UK T+1 from 11 Oct 2027; draft Central Securities Depositories (Amendment) (Intended Settlement Date) Regulations 2026 published Nov 2025, not yet made (checked 2026-10-24)
`XSWX`	T+1	2027-10-11	announced, not final	swissSPTC recommendation (acknowledged by SIF) for T+1 from 11 Oct 2027; SIX rule-book change pending
`BVMF`	T+2	—	in effect	B3 equities T+2
`XJSE`	T+3	—	in effect	JSE equities T+3
`XTKS`	T+2	—	in effect	JPX cash equities T+2 (since 16 Jul 2019)
`XHKG`	T+2	—	in effect	HKEX CCASS T+2
`XSHG`	T+1	—	in effect	SSE A-shares: securities T+0, cash T+1 (modelled as T+1)
`XKRX`	T+2	—	in effect	KRX equities T+2
`XSES`	T+2	—	in effect	SGX equities T+2
`XBOM`	T+1	—	in effect	SEBI T+1 rolling settlement (fully phased in 27 Jan 2023)
`XASX`	T+2	—	in effect	ASX CHESS T+2
`XNZE`	T+2	—	in effect	NZX T+2

Settlement dates are reference calculations for standard cash-equity trades. Your CSD, custodian or counterparty may apply different conventions (e.g. securities financing, primary market, cross-border links).

Errors

Errors are JSON: {"error": {"code": "…", "message": "…"}}.

HTTP	code	Meaning
400	`bad_date`, `missing_param`, `bad_n`, `bad_cycle`…	Fix the request
401	`invalid_key`	Unknown or revoked key
402	`plan_required`	That calendar needs a paid plan
404	`unknown_calendar`, `unknown_endpoint`	See `/v1/calendars`
422	`out_of_range`, `not_a_trading_day`	Outside 2020–2030 (or the calendar's data range), or trade date on a closed day (response includes `next_trading_day`)
429	`quota_exceeded`, `rate_limited`	Monthly quota or keyless hourly limit reached

OpenAPI, llms.txt and AI agents

Machine-readable spec: https://www.elcodev.com/apps/settledate/openapi.json (OpenAPI 3.1). Plain-text summary for LLMs: https://www.elcodev.com/apps/settledate/llms.txt. Agents can call the keyless endpoints directly for the free calendars.