Where the data comes from

Primary structured datasets at a glance

• Timezone rules and DST transitions are sourced from the IANA Time Zone Database (tzdata), refreshed on each upstream release. IANA tzdata
• Solar and lunar eclipse times come from NASA Goddard's Five Millennium Canon (Espenak & Meeus). NASA / GSFC eclipse catalogue
• Public holiday calendars combine the Nager.Date dataset, primary government release calendars, and a curated override layer. Nager.Date
• Federal Reserve rate-decision dates come from the FOMC official meeting calendar. Federal Reserve FOMC calendar
• US Government primary disclosure events are drawn from the National Archives release schedule. U.S. National Archives
• Hindu festival dates are aligned to drikpanchang.com's panchang calendar. Drik Panchang
• Islamic festival dates use the Umm al-Qura calendar (Saudi Arabia), cross-checked against the Fiqh Council of North America. Umm al-Qura calendar
• Jewish holiday dates are derived from Hebcal. Hebcal

Tech keynotes

tech-keynotes.json uses an intentionally layered methodology: the source class we accept depends on the confidence label attached to each keynote. The lower the confidence, the wider the source set — and the more visible the uncertainty in the user-facing UI.

Confirmed keynotes require an official vendor announcement or event page before we label a date confirmed. Typical sources include Apple Newsroom and apple.com/apple-events, the Google Keyword blog (blog.google) and Google I/O event pages, Microsoft's News Center and Build/Ignite event pages, Anthropic's press page (anthropic.com/news), OpenAI's blog, Meta Newsroom, Nvidia's GTC schedule, AWS re:Invent registration, and the equivalents for AMD, Samsung Newsroom, and Qualcomm. Older or imported entries that have not been rechecked keep a visible lower-confidence label until reviewed.

Expected, rumored, and estimated keynotes are necessarily sourced more broadly, because the vendor has not yet committed to a date in public. For these we use a weighted blend of:

• Prediction markets with meaningful liquidity (Polymarket, Kalshi) for consensus on whether and roughly when an event will happen.
• Tech-trade reporters with strong track records — Mark Gurman (Bloomberg) for Apple, Ming-Chi Kuo for Apple supply chain, The Information, The Verge, and similar outlets where the byline has a verifiable history of correctly calling these dates.
• Vendor-pattern estimates derived from the vendor's own multi-year cadence — e.g. WWDC has opened on the first or second Monday of June for many years, Google I/O is typically mid-May, re:Invent is the first week of December.
• Public hints from official accounts — invite-style social posts, executive interviews on the record, and earnings-call commentary that bracket a window.

The confidence label maps directly to the source quality: confirmed means the vendor has put the date on the record. expected, rumored, and estimated mean the date comes from the layered sources above and the page renders an explicit uncertainty window rather than a fixed date.

Disclosure events (government & legal)

disclosure-events.json is sourced from government primary materials and a small set of corroborating trade outlets. Primary sources include NARA (the US National Archives), the Department of Justice, the Securities and Exchange Commission EDGAR feed, the Federal Reserve's FOMC calendar, the European Central Bank's Governing Council schedule, the UK Office for National Statistics release calendar, and equivalent national statistics offices.

When a primary source is silent (e.g. a leaked timing for an imminent indictment), we corroborate against at least two independent trade outlets: Reuters, the Associated Press, Bloomberg, the Financial Times, the Wall Street Journal, the New York Times, the Washington Post. Trade-only signals are tagged speculative and do not get confidence: confirmed until the primary source publishes.

Major events (entertainment, sports, culture)

The curated entries in major-events.ts follow source rules by category. Film and TV release dates are checked against studio/distributor pages when those pages are available, with TMDb and IMDb used as structured reference aids rather than final authority. Sports fixtures prefer the relevant league or tournament source — FIFA, UEFA, the Olympic Committee, the NFL, NBA, MLB, NHL, the Premier League, and similar bodies — while provisional imports stay tagged until a primary fixture list is available. Tech-product launches require a vendor source before they are marked confirmed.

Religious festivals & public holidays

festivals.json and holidays.json defer to the religious authority for each tradition. Catholic and Christian feasts come from the USCCB liturgical calendar (United States Conference of Catholic Bishops) and the Vatican's general roman calendar. Jewish holidays come from Chabad.org and the Hebcal calendar. Islamic dates come from the Umm al-Qura calendar (Saudi Arabia) cross-checked against the Fiqh Council of North America. Hindu festival dates come from drikpanchang.com. Buddhist and Sikh observances prefer major sangha and gurdwara federation calendars respectively. Public-holiday pages combine the Nager.Date dataset, curated overrides, and primary government calendars where available. They are planning references, not legal advice, and local closures should be checked against the relevant authority when the date has legal or payroll impact.

Sports fixtures

sports-fixtures.json prefers the official governing body for each tournament: International Cricket Council (ICC) for international cricket, IPL official for the Indian Premier League, FIFA for international football, UEFA for European club competitions, the IOC for the Olympics, and the equivalent for tennis, F1, golf, rugby, athletics, and esports. Where a fixture is still provisional, the page keeps the lower confidence label and the final pre-event check happens against the organizer's current schedule.

Per-source confidence

Government primary sources are treated as authoritative. When a release calendar is published by NARA, the Federal Reserve, or a national statistics office, that date is the record — corrections come from the same source.

Trade press is corroborated against ≥2 outlets. A single Bloomberg story is never enough to flip a date to confirmed. We require two independent trade reports plus, ideally, a primary signal before a non-primary date is promoted.

Community claims are explicitly tagged. Tracked accounts and prediction markets contribute to the estimated window on rumour-tracker pages, never to confirmed dates. The community tier is always rendered behind the speculative-tracker UI so the reader knows what they are looking at.

Corrections & retractions

When a source publishes a correction we update the underlying catalogue and rebuild — the static page's dateModified reflects the change. When a date is publicly retracted (e.g. an event is cancelled), we mark the page retracted rather than deleting it, so the original prediction is preserved for accountability.

Spotted an error? Email the editorial team — see Editorial team.