Api MCP Server

Sunrise-Sunset.org API

The free Sunrise-Sunset.org API on GitHub: sunrise, sunset, twilight, golden hour, solar position and moon data for any place on Earth. Here you find ready-to-run examples, the OpenAPI spec, the announcements of every change and a place to report problems.

Stay up to date: click Watch → Custom → Releases at the top of this page and GitHub will tell you whenever the API changes.

• Free. No sign up, no API key.
• Simple. You send a latitude and longitude, you get JSON back.
• Attribution required. Credit sunrise-sunset.org wherever people can see where the data comes from (how).

Contents

• Quick start
• v1 or v2?
• Common pitfalls
• Examples
• For AI assistants (MCP)
• Usage limits and attribution
• Reporting problems
• License

Quick start (30 seconds)

Paste this into a terminal (or open the URL in your browser):

curl "https://api.sunrise-sunset.org/v2?lat=39.74&lng=-104.99&date=2026-08-15"

lat and lng are the latitude and longitude of the place, in decimal degrees (these are Denver, Colorado). You get back something like this (shortened):

{
  "date": "2026-08-15",
  "tzid": "America/Denver",
  "utc_offset": "-06:00",
  "sunrise": "2026-08-15T06:12:13-06:00",
  "sunset": "2026-08-15T19:55:56-06:00",
  "solar_noon": "2026-08-15T13:04:24-06:00",
  "day_length": 49423,
  "sun_status": "normal",
  "dawn": "2026-08-15T05:43:20-06:00",
  "dusk": "2026-08-15T20:24:43-06:00",
  "golden_hour": {
    "morning": { "begin": "2026-08-15T05:54:37-06:00", "end": "2026-08-15T06:49:15-06:00" },
    "evening": { "begin": "2026-08-15T19:19:00-06:00", "end": "2026-08-15T20:13:28-06:00" }
  },
  "moon_phase": "Waxing Crescent",
  "moon_illumination": 11.25
}

How to read it:

• Times use the ISO 8601 format. 2026-08-15T06:12:13-06:00 means 15 August 2026 at 06:12:13, local time, 6 hours behind UTC (the world reference time). Every programming language can read this format.
• The times are already in the local time of the place. You do not need to work out its timezone yourself: tzid tells you which one it is.
• day_length is in seconds (48841 seconds is 13 h 34 min).
• Leave out date to get today (today in that place, not where your server is).

Other parameters: date=tomorrow, date_start + date_end for a range of up to 366 days, tz to get the times in a different timezone, and time_format=unix for Unix timestamps. Every field is explained in the documentation.

v1 or v2?

There are two versions. Use v2 for anything new.

v1 is supported indefinitely and keeps working exactly as it does today, so existing code will not break. It also keeps its original calculation, so its sunrises are a little early and its sunsets a little late (by up to several minutes, depending on place and date). v2 fixes that.

Migration table and v1 docs: v2 docs, "Migrating from v1" and v1 documentation.

Common pitfalls

These are the problems we see most often in real integrations.

1. "The times are off by a few hours" (v1)

v1 answers in UTC unless you pass tzid. v2 answers in the place's local time by default. The same day in Denver:

v1  /json?lat=39.74&lng=-104.99&date=2026-08-15&formatted=0  ->  "sunrise": "2026-08-15T12:11:02+00:00"
v2  /v2?lat=39.74&lng=-104.99&date=2026-08-15                ->  "sunrise": "2026-08-15T06:12:13-06:00"

(The two are also about a minute apart: that is the v1 calculation issue mentioned above.)

In v2, tz must be a full timezone name like America/Los_Angeles. Abbreviations like PST are rejected with HTTP 400, so mistakes do not go unnoticed.

2. "Sunrise is on 1 January 1970" (v1)

Near the poles, on some days the sun never rises or never sets, and some twilights never happen. v1 still answers "status": "OK" but fills those fields with 1970-01-01T00:00:00+00:00 or 1970-01-01T00:00:01+00:00. Treat any 1970 date from v1 as "does not happen". Also, during the midnight sun v1 reports day_length 0.

v2 returns null instead and tells you why in sun_status. Utqiagvik, Alaska, on 21 December 2026:

{ "date": "2026-12-21", "tzid": "America/Anchorage", "sun_status": "polar_night",
  "sunrise": null, "sunset": null, "day_length": 0 }

sun_status is normal, midnight_sun (day_length 86400) or polar_night (day_length 0). Every event can be null on its own: near the polar circles the sun can rise one day without setting. Check each field before using it, and never work one out from another.

3. One request per day

If you show the same place every day, do not call the API every day. Ask for the whole year once with date_start and date_end:

curl "https://api.sunrise-sunset.org/v2?lat=39.74&lng=-104.99&date_start=2027-01-01&date_end=2027-12-31"

You get {"tzid", "lat", "lng", "days": [...]} with one entry per day. A range counts as a single request. Find days by their date field rather than by position: in rare cases a calendar day never existed in a place (Samoa skipped 30 December 2011) and it is left out.

4. Asking again for the same answer

The times for an explicit date never change, so save the response and reuse it forever. Responses for today and tomorrow can be kept until local midnight. The API sends the right Cache-Control headers, so browsers do this on their own.

5. HTTP 429 "Too many requests"

The API allows about 5 requests per second. The limit is mostly there so that a script stuck in a loop cannot slow the service down for everyone else: normal use never gets near it. Above that you get HTTP 429 with a Retry-After: 1 header: wait 1 second and retry, and if you get 429 again, double the wait each time (2, 4, 8 seconds...). The Python and JavaScript examples already do this. If you see 429s often, check your code for a loop, then fetch date ranges (pitfall 3) and cache the answers (pitfall 4).

6. Showing the time in the wrong timezone (JavaScript)

new Date(data.sunrise) reads the time correctly, but displaying that Date shows it in the viewer's timezone. If you want the place's own clock time, read it from the string: data.sunrise.slice(11, 16) gives "07:34".

7. !secret inside the URL (Home Assistant)

In Home Assistant, !secret only works as a whole YAML value. Written inside a URL, as in resource: https://api.sunrise-sunset.org/json?lat=!secret home_lat&..., it is sent literally. v1 reads that text as latitude 0 and longitude 0 and answers with the times of a point in the Atlantic, off the coast of Africa, with no error. Build the URL with resource_template and your home zone instead, as the Home Assistant example does:

resource_template: >-
  https://api.sunrise-sunset.org/v2?lat={{ state_attr('zone.home', 'latitude') }}&lng={{ state_attr('zone.home', 'longitude') }}

v2 rejects a latitude that is not a number with HTTP 400, so this kind of mistake shows up at once.

Examples

All examples use v2 and were tested against the live API.

Run them:

./examples/curl.sh                              # optional: ./examples/curl.sh 40.71 -74.01
python3 examples/python/sun_times.py 40.71 -74.01
node examples/javascript/sun-times.mjs 40.71 -74.01

Real output of the Python example for New York (run on 14 October 2026):

Today (2026-10-14, America/New_York):
  sunrise 07:06, sunset 18:17
  evening golden hour 17:40 to 18:34
  moon: Waxing Crescent (15.57% lit)

2027: 365 days fetched in one request.
  shortest day: 2027-12-21 (9.3 hours of daylight)
  2027-06-21: sunrise 05:25, sunset 20:30

Utqiagvik on 2026-12-21: sun_status=polar_night, sunrise=None, day_length=0

Plain HTTP (http://api.sunrise-sunset.org) works too, for IoT and embedded devices that cannot make TLS connections. Use HTTPS everywhere else.

From a web page, you can call the API directly with fetch(): requests from any website are allowed (CORS).

For AI assistants (MCP)

The same data is available as an MCP server, so AI assistants and agents can use it as a tool. No API key needed. Server URL:

https://api.sunrise-sunset.org/mcp

Claude Code:

claude mcp add --transport http sunrise-sunset https://api.sunrise-sunset.org/mcp

Setup for Claude, ChatGPT, Codex and Cursor: examples/mcp and the MCP guide.

Usage limits and attribution

• The API is free for reasonable request volumes. Use date ranges and caching to stay well under the limits.

• Attribution is required. Credit Sunrise-Sunset.org wherever people can see where the data comes from:

  • Websites and apps: a visible link to sunrise-sunset.org next to the data, or in the app's About or Credits screen. For example:

    Sun data by <a href="https://sunrise-sunset.org">Sunrise-Sunset.org</a>
    

  • Devices with a screen (TVs, clocks, dashboards, smart displays): the text "Sun data by Sunrise-Sunset.org" where the data is shown, or in the settings or About screen.

  • Projects without a screen (Home Assistant setups, scripts, firmware, voice assistants): a mention of sunrise-sunset.org in the README, the documentation or the store listing.

• Is the API down? Check the API status page.

Reporting problems

Found a wrong time, a confusing response or a broken example? Open an issue in this repository. Include the full request URL, what you expected, what you got, and the date and timezone you had in mind.

For other questions, use the contact page.

License

The example code in this repository is under the MIT License: copy it into your own projects freely.

The license covers the code only. The data returned by the API has its own terms: it is free to use with the attribution described above. See the API documentation.