# Prism Lab vs Extempore

The clearest difference is rating: Prism Lab at 3.3 against Extempore's 2.4. Prism Lab also leads on review sentiment (80% vs 49%) and ratings volume (287 vs 85). Extempore's advantage is in-app purchases (none vs 1) and update cadence (every 2 months vs every 216 months). On price, ads, monetization model and device support there is nothing between them.

Both are free to download. Prism Lab sells 1 one-off in-app purchase. Extempore asks for nothing beyond the download.

Prism Lab holds the better App Store score, 3.3 against 2.4. Both are backed by a comparable volume of ratings — 287 and 85 respectively. Written reviews point the same way: 80% of Prism Lab's written reviews are positive against 49% of Extempore's.

Prism Lab ships an update every 216 months, Extempore every 2 months. The most recent releases landed on October 31, 2026 and November 6, 2026 respectively.

## The numbers

| Metric | Prism Lab | Extempore |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.3 (287 ratings)](https://appshunter.io/ios/app/prism-lab/id301875263/reviews)** | [2.4 (85 ratings)](https://appshunter.io/ios/app/extempore/id1062018455/reviews) |
| Number of ratings | **287** | 85 |
| Positive reviews | **80.0% of reviews** | 48.8% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 216 months | **Every 2 months** |
| Monetization | Free | Free |
| Size | 2 MB | 56 MB |
| Requires iOS | 17.0 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [KZ Labs](https://appshunter.io/developer/1091008972) | [Deeloh Technologies LLC](https://appshunter.io/developer/1062018454) |

## What reviewers say

### Prism Lab

[App page](https://appshunter.io/ios/app/prism-lab/id301875263)

This application simulates lasers passing through prisms, demonstrating light refraction and reflection using Snell's Law. Users can adjust light sources, materials, and prism shapes to observe how light's trajectory changes between environments. It's a practical tool for understanding optical principles.

**Highlights:** Laser refraction simulation, Snell's Law implementation, Adjustable light source, Variable prism shapes, Different material options, Angle calculation

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Buy me a coffee | $2.99 | one-time |


### Extempore

[App page](https://appshunter.io/ios/app/extempore/id1062018455)

Facilitates asynchronous video and audio assignments for foreign language learners and educators. Ensures spontaneous speech by preventing the use of prepared scripts.

**Highlights:** Asynchronous video/audio assignments, Extemporaneous speech enforcement, No need for scheduled interviews, Reduces class time for speaking, Instructor-created assignments

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 👍 Handy for speaking exercises
- 👍 Good for practicing speaking
- 👍 Great for Chinese practice
- 👍 Amazing enjoyment
- 👍 Works great for Spanish

**What reviewers complain about**

- 🐛 Struggles with issues
- 🐛 Leads to bad scores
- 🐛 Keeps locking assignments
- 🐛 Glitchy and terrible
- 🐛 Recording issues

**Reported bugs**

- App keeps locking assignments
- Recording issues
- Disappearing UI elements after stopping recording
- Error message: 'Error. Sorry, this question is unavailable.'
- App is slow and unusable

**Requested features**

- Allow users to use web version on mobile


## Frequently asked questions

### Is Prism Lab free?

Prism Lab is free to download, with in-app purchases available.

### Is Extempore free?

Extempore is free to download, with no in-app purchases.

### Which has better reviews, Prism Lab or Extempore?

Prism Lab is rated higher. Prism Lab averages 3.3 out of 5 from 287 ratings, while Extempore averages 2.4 from 85 ratings.

### Do Prism Lab or Extempore have ads?

Neither Prism Lab nor Extempore shows ads.

### Which is updated more often, Prism Lab or Extempore?

Prism Lab ships an update every 216 months, and Extempore every 2 months. Most recently, Prism Lab was updated on October 31, 2026 and Extempore on November 6, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*