Where the data comes from

Primary structured datasets at a glance

• Time-zone rules and DST transitions come from the IANA Time Zone Database (tzdata) as bundled with the JavaScript runtime that renders the page; a new tzdata release reaches the site when that runtime is updated. 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 were compiled with reference to published panchang calendars such as Drik Panchang. Drik Panchang
• Islamic festival dates were compiled with reference to the Umm al-Qura calendar (Saudi Arabia); actual dates can differ by a day or two by country, depending on moon sighting. Umm al-Qura calendar
• Jewish holiday dates were compiled with reference to Hebcal. Hebcal

Tech keynotes

The tech-keynote catalogue 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. Some older entries currently link only to the vendor's homepage rather than the specific announcement; we are replacing those links as we review each entry.

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 draw on:

• Prediction markets (Polymarket, Kalshi). Live market prices are shown on the page for context on whether and roughly when an event will happen, and are not part of the weighted-median estimate. A dated market snapshot recorded in an event's signal log is counted like any other trade-tier signal.
• 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)

The disclosure-events catalogue 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 reported but unannounced timing), we rely on established news organisations such as Reuters, the Associated Press, Bloomberg and the Financial Times, and label the date as speculative. Dates based only on news reports are not labelled confirmed until the primary source publishes.

Major events (entertainment, sports, culture)

The curated entries in the major-events catalogue 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. Separately, film, TV and game countdowns imported from the TMDb, TVmaze and RAWG feeds take their date, and their “confirmed” label, from those databases; we do not check each of those entries against the studio or publisher.

Religious festivals & public holidays

The festival and holiday catalogues were compiled with reference to published calendars for each tradition: the Western and Orthodox church calendars for Christian feasts, Hebcal for Jewish holidays, the Umm al-Qura calendar for Islamic dates, and panchang calendars such as Drik Panchang for Hindu festivals. The festival catalogue does not yet store a source link for each entry; we are adding them as we review. Lunar and lunisolar dates can differ by a day between countries and communities, so check with your local religious authority if the exact day matters. 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

The sports-fixtures catalogue 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 never confirms a date on its own. A news report, however reliable the outlet, is logged as a trade-tier signal. A date is labelled confirmed only when the organiser announces it, except for the database-fed film, TV and game countdowns described under major events, which take their label from those databases.

Community claims are explicitly tagged. Tracked accounts contribute to the estimated window on rumour-tracker pages, never to confirmed dates. Live prediction-market prices are shown alongside for context and do not feed the estimate; a dated market snapshot in the signal log counts as a trade-tier signal.

Corrections & retractions

When a source publishes a correction we update the underlying catalogue at our next review and redeploy. Updates are manual, so there can be a delay. If an event is cancelled, we update its page rather than deleting it.

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