For developers

Candle lighting and the full day’s zmanim for San Jose, as JSON. No key, no sign-up. Use it in your own site, a home-screen widget, or a script.

Try it now

All four work in a terminal, in a browser address bar, or from any page on the internet — access-control-allow-origin is open.

curl https://siliconchabad.com/api/shabbat
curl https://siliconchabad.com/api/zmanim
curl "https://siliconchabad.com/api/zmanim?date=2026-12-25"
curl "https://siliconchabad.com/api/shabbat?weeks=8"

What comes back

This is the real answer from /api/shabbat, generated when you loaded this page — not an example somebody typed out once.

{
  "label": "Shabbat",
  "candleLighting": {
    "iso": "2026-09-18T18:52:00.000-07:00",
    "local": "6:52 PM"
  },
  "havdalah": {
    "iso": "2026-09-19T19:47:00.000-07:00",
    "local": "7:47 PM"
  }
}

Every time is sent twice: iso for a machine, with the offset attached, and local as the clock on the wall in San Jose reads it. That is deliberate — slicing a date off a UTC timestamp gives you tomorrow from five in the afternoon Pacific, and we have shipped that bug four times in our own code.

In a page

const r = await fetch('https://siliconchabad.com/api/shabbat');
const { windows } = await r.json();
document.querySelector('#candles').textContent =
  `Candle lighting ${windows[0].candleLighting.local}`;

In a script

import urllib.request, json

with urllib.request.urlopen("https://siliconchabad.com/api/shabbat") as r:
    w = json.load(r)["windows"][0]

print(w["label"], "candles", w["candleLighting"]["local"])

How the times are computed

Not from a library’s defaults. Every angle follows Chabad.org’s own published definitions for this location:

• Dawn at 16.9° below the horizon — Chabad.org’s figure, not the common 16.1°.
• Earliest tallis and tefillin at 10.2°.
• Nightfall at 6°.
• The proportional hour measured between hanetz amiti and shkiah amitis — the geometric horizon, not the sunrise an almanac prints — divided by twelve, in the Alter Rebbe’s reckoning.
• Candle lighting eighteen minutes before sunset.
• When Shabbat ends at 8.5°, which is a later time than nightfall. They are two different numbers and the API sends both, because reading one as the other means finishing Shabbat early.

The last one is calibrated rather than merely documented: it is checked against Chabad.org’s own published times for two San Jose dates and asserted to the minute by a test that runs on every change. An earlier calibration against a single date was four minutes out, and the second date is what caught it.

What it will not do

• It is San Jose only. Latitude 37.2214, longitude −121.8622. Used from Los Angeles it is about forty minutes wrong and every number still looks plausible, so each response repeats where it is for.
• It reads no database, which is why it is fast, cached, and cannot be down when the rest of the site is. It also means the Shul’s own calendar is not in it.
• It is not a psak. These are computed times. For what to do with one, ask a person — that is what the phone number and the chat are for.

Using it

Freely, including commercially, with no key and no attribution required — though a link back is kind. There is no rate limit; please cache rather than poll. Every response carries cache-control, so a browser or a proxy will hold the answer for you — and the zmanim for a given date never change, which is why an explicit ?date= is cached for a day. If you are going to depend on it for something that matters, tell us so we know it is there.

The code is open: packages/hebrew-calendar in the repository, with the tests that pin every number on this page.

Today in San Jose, for the record: dawn 5:27 AM, sunrise 6:50 AM, midday 1:02 PM, sunset 7:14 PM, nightfall 7:41 PM. All of them, every day: Shabbat & holiday times.