iStellar vs Koudo
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
iStellar
Explore the cosmos with a realistic planetarium experience. View the night sky from any location and time, with detailed celestial bodies and dynamic simulations. Intuitive multi-touch controls make navigation effortless.
- Real-time starry sky simulation
- Adjustable location and time
- Detailed celestial object data
- Intuitive multi-touch controls
- Solar eclipse simulation
- Object search function
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iStellar is a planetarium App that shows the starry sky seen from the place and time of your choice. It is optimized for Multi-Touch control, allowing you to operate intuitively; drag to move the star chart, pinch to zoom in and out, and so on. The star chart can be rotated from portrait to landscape, and you can even fix the location via GPS (only for iPhone 3G). FEATURES - Over 16,000 star data, with name for 254 stars - Twinkles like actual stars - Simulates distortion (atmospheric refraction and extinction) at low altitude - Displays the Sun, daylight, twilight, the Moon (with shape and phase), 8 planets, Pluto - Shows name, line and picture for all constellations - Milky Way with real tone - Plots Messier objects and their names - Comets with accurate position and magnitude. Data can be downloaded whenever available - Meteor Shower Radiants - Solar eclipse simulation with high accuracy - Adjustable moonlight and light polution - Landscape and azimuth / direction grid - Beautiful animation (real-time, adjusted time, reversal) - Simulates every second between 1 Jan 1900 to 31 Dec 2099 - Switches screen according to the device's orientation - Zoom by pinching(3 to 180 degrees) - Easy moving through the sky by dragging, and centering by double-tap - Object Search function - Free choice of location and time zone, instant setting with GPS
Koudo
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Koudoは、ただの線で終わらせない、移動を追体験できるGPSアプリです。スマートフォンのGPSと気圧センサーを組み合わせて、高精度な位置・高度・速度を記録します。 【最大の特徴:没入型リプレイ機能】 移動の記録を時間を遡って再生。地図上のアニメーションと速度・高度・気圧のグラフが完全に連動し、「あの坂道で何km/h出ていたか」「トンネルでどれだけ高度が下がったか」「飛行機の機内は何hPaだったか」を視覚的に振り返れます。グラフの任意のポイントをタップすれば、その瞬間の地図位置にジャンプ。まるでドライブレコーダーのように、移動の全容を把握できます。 【主な機能】 ・GPS + 気圧センサーによる高精度な高度計測 ・速度・高度・気圧のリアルタイム表示 ・記録間隔の設定(1秒/5秒/10秒/30秒) ・地図上での軌跡表示 ・速度・高度・気圧のグラフ表示(色分けで直感的) ・GPXファイルのエクスポート・インポート ・CSVエクスポート ・移動モード別のアイコンカスタマイズ 【こんな方におすすめ】 ・ウォーキング、ランニング、サイクリングの記録 ・登山やハイキングの高度変化を記録 ・飛行機搭乗時の気圧変化を観測 ・ドライブや旅行の軌跡を詳細に振り返りたい ・GPSデータの精密な分析 【プライバシー】 記録データはすべて端末内に保存。外部への自動アップロードなし。位置情報の送信は地名取得時のみ。
Screenshots
Verdict
The clearest difference is update cadence: Koudo at every 5 days against iStellar's every 3 months. On ads, in-app purchases, device support and iOS requirement 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
iStellar ships an update every 3 months, Koudo every 5 days. The most recent releases landed on September 27, 2026 and August 23, 2026 respectively.
| Parameter | iStellar | Koudo |
|---|---|---|
| Price | $3.99 — better | — |
| Rating | 4.0 (1 ratings) — better | — |
| Positive reviews | 49.3% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 3 months | Every 5 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | — |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 12.4 — better | 13.0 |
| Further details — not scored | ||
| Size | 37 MB | 25 MB |
| Age rating | 4+ | 4+ |
| Developer | AstroArts Inc. | Hajime Kato |
In-app purchases
iStellar
No in-app purchases
Koudo
No in-app purchases








