Comparison

OpenWindow vs Aerzeit

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

OpenWindow

This app provides clear, practical recommendations on whether to open your windows or go outside. It combines local weather and air-quality data into simple guidance for everyday decisions.

Highlights
  • Window and outdoor activity recommendations
  • Hourly weather and air quality outlooks
  • Local and manual location search
  • Saved default location
  • Unit preferences
  • Light and dark mode
Features
Read full description

OpenWindow helps you decide when the air outside is worth letting in. Check whether it is a good time to open your windows or go outside using local weather and air-quality conditions. OpenWindow combines temperature, humidity, precipitation, wind, visibility, UV, and air-quality data into clear, practical recommendations. Instead of making you interpret every weather metric yourself, OpenWindow gives you simple guidance for two everyday questions: - Is it a good time to open the windows? - Is it a good time to go outside? Features: - Current recommendations for windows and outdoor activity - Hourly outlooks so you can plan around better conditions - Weather and air-quality data powered by Open-Meteo - Current-location lookup with optional location permission - Manual location search if you prefer not to use device location - Saved default location for quick checks - Unit preferences for temperature, wind, visibility, and more - Light and dark mode support - No account required OpenWindow is built for quick, low-friction decisions: checking the room before opening a window, planning a walk, timing errands, or seeing whether air quality makes staying inside the better call. Location access is optional and used only to fetch local weather and air-quality data. You can always search for a location manually instead.

About

Aerzeit

This app analyzes outdoor conditions for the next 48 hours to identify optimal times for ventilation. It allows customization of temperature ranges and environmental factors like rain, humidity, and pollen to help you decide when to open windows.

Highlights
  • 48-hour outdoor condition forecast
  • Customizable temperature ranges
  • Rain, humidity, wind, air quality, pollen filters
  • UV and sun position tracking
  • Apple Watch app and complication
  • Home Screen widget
  • Multi-language support
Features
Read full description

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 (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

OpenWindow4 screens
Aerzeit4 screens

Verdict

The call

The clearest difference is in-app purchases: OpenWindow at none against Aerzeit's 1. Aerzeit's advantage is iOS requirement (16.4 vs 26.0). On price, rating, ratings volume and update cadence 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Aerzeit sells 1 in-app purchase, starting at $9.99 per year. OpenWindow asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 5.0 for OpenWindow against 5.0 for Aerzeit. Both are backed by a comparable volume of ratings — 1 and 1 respectively.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 3 days. Both last shipped on November 5, 2026.

Scorecard3 real differences · 6 level
OpenWindow versus Aerzeit: the parameters behind the verdict, then further details
ParameterOpenWindowAerzeit
PriceFreeFree
Rating5.0 (1 ratings)5.0 (1 ratings)
Number of ratings11
Update frequencyEvery 3 daysEvery 3 days
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFreemium
DevicesiPhone, iPad, MaciPhone, iPad, Apple Watch
Requires iOS26.016.4 — better
Further details — not scored
Size18 MB28 MB
Age rating4+4+
DeveloperSouth Bay Compute, LLCSamuel Harrold

Customer experience

OpenWindow

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

Aerzeit

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

OpenWindow

No in-app purchases

1 purchases

Aerzeit

Subscriptions1
  • Aerzeit Premium$9.991 Year

Questions

Is OpenWindow free?
OpenWindow is free to download, with no in-app purchases.
Is Aerzeit free?
Aerzeit is free to download, with in-app purchases available.
Which has better reviews, OpenWindow or Aerzeit?
OpenWindow and Aerzeit are both rated 5.0 out of 5 on the App Store, from 1 and 1 ratings respectively.
Do OpenWindow or Aerzeit have ads?
Neither OpenWindow nor Aerzeit shows ads.
Which is updated more often, OpenWindow or Aerzeit?
OpenWindow ships an update every 3 days, and Aerzeit every 3 days. Most recently, OpenWindow was updated on November 5, 2026 and Aerzeit on November 5, 2026.

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