Our Methodology
Transparency about how we produce our data matters. This page documents the sources, algorithms, and editorial processes behind every calculation and piece of content on TimeandTool.
Data Sources
Sun & Moon Calculations
All sunrise, sunset, golden hour, blue hour, and moon phase data is computed in pure TypeScript using our own astronomy library. The algorithms are based on Jean Meeus' Astronomical Algorithms (2nd ed.), the standard reference for computational astronomy. No external API calls are made for solar or lunar data — calculations are performed server-side from the user's coordinates.
For verification against official government data, we cross-reference with the US Naval Observatory (USNO), which publishes authoritative sun and moon data for thousands of locations worldwide.
Timezone Data
Timezone conversions, UTC offsets, and DST rules are derived from the JavaScript Intl.DateTimeFormat API, which is backed by the IANA Time Zone Database (also known as the Olson Database or tz database). The IANA database is the authoritative global source for timezone rules used by virtually every operating system and programming language. It is updated whenever a government changes its timezone rules.
We never hardcode UTC offsets — all timezone operations use IANA identifiers (e.g., America/New_York) to ensure DST transitions are handled correctly.
Public Holiday Data
Holiday data for all supported countries is sourced from the Nager.Date public API, an open-source project that maintains government-verified holiday data for 100+ countries. Our holiday pages use Incremental Static Regeneration (ISR) with a 24-hour revalidation window, so data is refreshed daily and changes propagate within one day.
For editorial content about holiday history and cultural context, our team researches primary government and cultural sources and all content is reviewed by a subject-matter expert before publication.
Update Frequency
| Content Type | Update Frequency | Source |
|---|---|---|
| Sunrise & Sunset data | Calculated on-demand | Pure TypeScript (lib/astronomy/) |
| Moon phases | Calculated on-demand | Pure TypeScript (lib/astronomy/) |
| Public holidays | Daily (ISR revalidation) | Nager.Date API |
| Timezone rules | Updated with OS/runtime | IANA Time Zone Database via Intl API |
| Blog & guide content | Editorial review cycle | Expert authors + peer review |
| Calendar data | Static / pre-generated | ISO 8601 / Gregorian rules |
Expert Review Process
All editorial content on TimeandTool — blog posts, long-form guides, and tool explanations — is written by domain experts and undergoes a peer review process before publication. Primary authors are specialists in their fields: our timezone content is written by a geospatial engineer with 12 years of timezone-infrastructure experience; our astronomy content comes from a PhD astrophysicist specialising in precision timekeeping; our calendar and holiday content is authored by a cultural historian focused on calendar systems. Where relevant, articles are cross-reviewed by a second expert from a complementary discipline before going live.
Meet the team behind the content:
Accuracy & Corrections
We are committed to accuracy. If you find an error in any calculation, data point, or article, please contact us at support@timeandtool.com. We investigate all reported issues and publish corrections promptly.