Sunrise-Sunset.io has been a reliable choice for developers who need sun position data. It's free, requires no API key, and returns exactly what its name promises. If that's all you need, it works well.

This comparison is for developers who've started with Sunrise-Sunset.io and now find themselves needing more — moon data, golden hour times, or other world data endpoints alongside their sun calculations.

Sunrise-Sunset.io focuses on one thing: sun times. You send coordinates and a date, and you get back:

• Sunrise and sunset times

• Solar noon

• Day length

• Civil, nautical, and astronomical twilight times

No signup, no API key, no cost. For basic sunrise/sunset lookups, this simplicity is genuinely appealing.

The gaps in Sunrise-Sunset.io become apparent when your application requirements expand:

No moon data. Sunrise-Sunset.io is sun-only. If you need lunar phases, moonrise/moonset times, or moon illumination for photography apps or tide calculators, you'll need a second API.

Single-purpose API. When your app also needs holidays, timezone conversions, or geographic data, you're managing multiple API integrations.

World Data API includes everything Sunrise-Sunset.io provides, plus:

Beyond astronomy, you also get access to holidays, timezone data, business day calculations, geographic information, and travel reference data — all through a single API.

This is the honest part of the comparison: Sunrise-Sunset.io is free. World Data API is not.

Our astronomy endpoints require a paid subscription starting at $9/month or $79/year. If you only need basic sun times and cost is a primary concern, Sunrise-Sunset.io remains a reasonable choice.

The calculation changes when you need moon data or blue hour times, or when you also need holidays, timezones, or geographic data. Adding separate APIs for each data type — at some point, a single paid subscription becomes simpler and more cost-effective.

A few things to know about astronomical calculations in general:

Calculated vs observed times. Both APIs return calculated times based on algorithms. Actual observed sunrise and sunset can differ by a few minutes due to atmospheric conditions, elevation, and local terrain.

Polar regions. During polar day or polar night, standard sunrise/sunset times don't apply. World Data API returns indicators for these conditions rather than nonsensical times.

Consider World Data API when:

• You need moon phases, moonrise/moonset, or lunar illumination data

• Your app requires blue hour calculations (Sunrise-Sunset.io doesn't include this)

• You're already managing multiple APIs for different world data

• You want a single integration point for astronomical, geographic, and calendar data

Stick with Sunrise-Sunset.io when:

• Basic sun times are all you need

• Free matters more than features

• You prefer no-signup simplicity for a small project

If you're currently using Sunrise-Sunset.io and want to try World Data API, you don't need to replace your existing integration immediately. You can add World Data API for the endpoints you're missing — moon data, golden hour — and migrate your sun time calls later if you choose.

The response formats differ, so you'll need to adjust your parsing logic, but the core data (coordinates in, times out) follows the same pattern.

World Data API astronomy features are included in all paid plans:

This includes the full API — astronomy, holidays, timezones, business days, geographic data, and travel reference data.

Sunrise-Sunset.io is free with no usage limits published.

Sunrise-Sunset.io is a solid free option for basic sun data. When your needs grow to include moon phases, golden hour calculations, or other world data, World Data API provides a natural upgrade path. You're not replacing something broken — you're extending your capabilities.