GravLens3 vs ExpiWell
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
GravLens3
Simulate the effects of gravitational lensing on your iPhone or iPad. Adjust lens parameters and apply distortions to your photos or live camera feed. Share your creations or project them for educational purposes.
- Simulate Hubble Space Telescope images
- Adjust lens size and ellipticity
- Distort photos from library or camera
- Live real-time lensing view
- AirPlay and external monitor support
- Save and share distorted images
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Gravitational lensing is a remarkable astrophysical phenomenon, where the light of a distant galaxy is bent by a massive foreground galaxy. Now you can simulate the effect of a gravitational lens on your iPhone or iPad! With GravLens3, a remarkable and educational tool you can: * Simulate Hubble Space Telescope images of strong gravitational lenses * Adjust the size and ellipticity of the lens model * See the distortion on a picture from your photo library or camera * Save the image, tweet it, post to Facebook, or print it * Live View: view the world through a gravitational lens! Real-time lensing with your camera. * Airplay and external monitor support. Broadcast your lensing to an external projector or Apple TV. Great for lectures! * Retina display, iPhone 6/6 plus all supported.
ExpiWell
This app facilitates experience sampling and ecological momentary assessment for research. It allows users to share opinions and experiences through surveys and daily diaries, ensuring data privacy. Researchers can collect valuable insights through this platform.
- Experience sampling method (ESM)
- Ecological momentary assessment (EMA)
- Surveys and mood tracking
- Daily diary entries
- Just-in-time adaptive interventions (JITAI)
- Digital ethnography
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ExpiWell is the premier experience sampling method (ESM) and ecological momentary assessment (EMA) app for surveys, mood tracking, daily diary, just-in-time adaptive interventions (JITAI), and digital ethnography. Market researchers, polling companies, and social scientists want your valuable opinions and experiences. Using our free app, you can share your experiences and opinions. We have real surveys that you can take. ExpiWell® ensures your privacy. We will not forward, sell, or transfer your information. ExpiWell Privacy Policy - https://app.expiwell.com/privacy ExpiWell Terms of Use - https://app.expiwell.com/tos
Screenshots
Verdict
The clearest difference is rating: ExpiWell at 4.6 against GravLens3's 3.7. ExpiWell also leads on update cadence (every 5 days vs every 17 months) and ratings volume (1.5K vs 6). GravLens3's advantage is review sentiment (80% vs 39%) and iOS requirement (6.1 vs 15.0). On price, ads, in-app purchases and monetization model 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. Neither carries in-app purchases, so what you see is what you pay.
ExpiWell holds the better App Store score, 4.6 against 3.7. That said, the two scores are not equally well evidenced: ExpiWell has 1.5K ratings behind it against 6, so its average is the more settled of the two. Written reviews complicate that: 80% of GravLens3's written reviews are positive against 39% of ExpiWell's, so the app with the better star average is not the one people write more warmly about.
GravLens3 ships an update every 17 months, ExpiWell every 5 days. The most recent releases landed on October 23, 2026 and November 1, 2026 respectively.
| Parameter | GravLens3 | ExpiWell |
|---|---|---|
| Price | Free | Free |
| Rating | 3.7 (6 ratings) | 4.6 (1.5K ratings) — better |
| Positive reviews | 80.0% of reviews — better | 39.3% of reviews |
| Number of ratings | 6 | 1.5K — better |
| Update frequency | Every 17 months | Every 5 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 6.1 — better | 15.0 |
| Further details — not scored | ||
| Size | 4 MB | 36 MB |
| Age rating | 4+ | 4+ |
| Developer | Eli Rykoff | Expiwell, Inc. |
Customer experience
GravLens3
ExpiWell
Bugs and requests
GravLens3
Not enough reviews yet to summarise bugs or requests.
ExpiWell
Reported bugs
3 issues- Login issues
- Incompatibility with certain devices
- Crashing during surveys
Requested features
2 requests- Better notification system
- More seamless interface
In-app purchases
GravLens3
No in-app purchases
ExpiWell
No in-app purchases
