SunSpan vs Aerzeit
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SunSpan
Visualize an entire year of daylight, sunrise, sunset, and twilight on a single, intuitive chart. Easily inspect daily solar times and phases by tapping or dragging across the visual representation. Offers detailed insights into seasonal changes and astronomical events.
- Full-year daylight chart
- Eight-stop twilight gradient
- Inspect daily solar times
- DST transitions marked
- Location picker via map/GPS
- Automatic time zone resolution
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SunSpan — A Year of Daylight on One Screen SunSpan renders an entire year of sunrise, sunset, and twilight as a single chart. Each day is a vertical band shaded from astronomical night through nautical and civil twilight into full daylight, so the seasonal curve, the solstices, the equinoxes, and effects like white nights and polar day are visible at a glance. Tap or drag across the chart to select any day and see its sunrise, sunset, daylight length, and twilight phase times in a detail bubble. Features - Full-year daylight chart for any location, any year from 1900 to 2100 - Eight-stop twilight gradient: night, astronomical, nautical, civil, day - Tap or drag any day to inspect sunrise, sunset, daylight length, and twilight phase times - DST transitions marked on the chart - Location picker via satellite map, or automatic from device GPS - Time zone resolved automatically from the selected coordinates - Localized in English, Spanish, German, and Ukrainian Privacy No accounts, no analytics, no ads. Location is used only on-device to compute solar geometry and never leaves the device.
Aerzeit
This app analyzes local weather forecasts to suggest optimal times for opening windows to ventilate your home with fresh air. It allows customization of preferred temperature ranges and filters for rain, humidity, wind, air quality, and pollen.
- Optimal window opening times
- Customizable temperature ranges
- Rain, humidity, wind filters
- Air quality and pollen alerts
- 48-hour forecast chart
- Apple Watch companion app
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Aerzeit watches the next 48 hours and tells you the stretches when the air outside is in the temperature range you chose — so you know when it's worth opening up instead of leaving the system running. When nothing in the next two days is worth it, it says so. Everything else is yours to switch on: rain, humidity, wind, air quality, pollen, UV, sun position, and the hours you'd actually consider opening. Set it once for your climate and your house, wherever in the country you are. WHAT IT DOES Pick the outdoor temperature range you'd be happy to let in. Aerzeit watches the local forecast and tells you when conditions match — once a day, at a time you choose. It can also tell you the moment a window opens, and the moment to close it again. Turn on the filters that matter where you live: rain, humidity, wind, air quality, pollen, UV, and the hours of the day you'd actually consider opening up. Set a shortest and longest opening, so you don't hear about gaps too brief to use or leave one open longer than you meant to. A 48-hour chart shows every condition in one place, so you can see where they agree and where they don't. Tap "Use current location" to set a spot to roughly 1 km precision, or search for a town. A companion Apple Watch app and complication show the same at-a-glance status on your wrist, and keep themselves current even when your phone is elsewhere. A Home Screen widget shows the next open-window period at a glance. Aerzeit runs in 50 languages, picked on the Locations page beside °C/°F. WHAT IT DOESN'T DO Aerzeit doesn't model your home — it reports the outdoor conditions and leaves the judgement to you. Opening, sizing and timing the actual airing is yours. It reports public weather and environmental data (including air quality, pollen and UV) as a comfort tool, not medical advice; if a health condition makes any of those matter for you, follow your clinician's guidance. PRIVATE BY DESIGN - Empty Privacy Manifest. The app calls none of Apple's required-reason APIs. - No language detection. Aerzeit never reads your phone's language setting — that's one of the required-reason APIs it avoids — so you pick from 50 languages in the app instead. - Minimal data. To fetch a forecast, the app sends a roughly 7 km grid cell to Aerzeit's server — no account, no identifiers, no raw GPS, no history. Your temperature range and all your filter settings stay on your device. The data export (Settings → Export my data) shows exactly what's held — it's all on your phone. - No accounts. No analytics. No tracking. No advertising. No third-party SDKs beyond a small geospatial maths library. MADE INDEPENDENTLY Aerzeit is built and published by Samuel Harrold, based in Indianapolis, Indiana, USA. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is in-app purchases: SunSpan at none against Aerzeit's 1. SunSpan also leads on update cadence (every 2 days vs weekly). On price, rating, ratings volume and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Aerzeit sells 1 in-app purchase, starting at $9.99 per year. SunSpan asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 5.0 for SunSpan against 5.0 for Aerzeit. Both are backed by a comparable volume of ratings — 1 and 1 respectively.
SunSpan ships an update every 2 days, Aerzeit weekly. The most recent releases landed on October 11, 2026 and October 21, 2026 respectively.
| Parameter | SunSpan | Aerzeit |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) | 5.0 (1 ratings) |
| Number of ratings | 1 | 1 |
| Update frequency | Every 2 days — better | Weekly |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Freemium |
| Devices | iPhone, iPad | iPhone, iPad, Apple Watch — better |
| Requires iOS | 16.0 — better | 16.4 |
| Further details — not scored | ||
| Size | 6 MB | 27 MB |
| Age rating | 4+ | 4+ |
| Developer | Mykhailo Chelnokov | Samuel Harrold |
In-app purchases
SunSpan
No in-app purchases
Aerzeit
- Aerzeit Premium$9.991 Year









