# Diffraction Grating Calculator vs Private LLM

The clearest difference is update cadence: Private LLM at every 6 weeks against Diffraction Grating Calculator's every 29 months. Private LLM also leads on chart position (#23 vs unranked). Diffraction Grating Calculator's advantage is price ($2.99 vs $4.99) and iOS requirement (13 vs 17.0). On ads, in-app purchases and device support there is nothing between them.

Diffraction Grating Calculator costs $2.99 and Private LLM $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Diffraction Grating Calculator ships an update every 29 months, Private LLM every 6 weeks. The most recent releases landed on September 29, 2026 and October 18, 2026 respectively.

## The numbers

| Metric | Diffraction Grating Calculator | Private LLM |
| --- | --- | --- |
| Price | **$2.99** | $4.99 |
| Rating | — | **[4.2 (719 ratings)](https://appshunter.io/ios/app/private-llm-local-ai-chat/id6448106860/reviews)** |
| Number of ratings | — | **719** |
| Positive reviews | — | 48.7% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 29 months | **Every 6 weeks** |
| Monetization | — | Paid |
| Best chart rank | — | **#23** |
| Size | 1 MB | 1.3 GB |
| Requires iOS | **13** | 17.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Age rating | 4+ | 12+ |
| Developer | [Nitrio](https://appshunter.io/developer/321121189) | [Numen Technologies Limited](https://appshunter.io/developer/1683507194) |

## What reviewers say

### Diffraction Grating Calculator

[App page](https://appshunter.io/ios/app/diffraction-grating-calculator/id1413088894)

**Features:** macOS Compatibility

**In-app purchases:** none


### Private LLM

[App page](https://appshunter.io/ios/app/private-llm-local-ai-chat/id6448106860)

**Currently charting:** #23 Top Paid · Utilities, #145 Top Paid (US App Store)

This AI assistant runs entirely on your device, ensuring all your conversations remain private and offline. Choose from a wide variety of open-source language models and customize interactions for personalized assistance.

**Highlights:** On-device AI processing, Wide selection of open-source LLMs, Offline functionality, Siri and Shortcuts integration, Customizable system prompts, One-time purchase with Family Sharing

**Features:** Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 🚀 Amazing AI app
- 🔒 Privacy-focused local LLM app
- 👍 Optimized for Apple devices
- 👍 Wonderful developers and great community
- 👍 Plenty of models to choose from

**What reviewers complain about**

- 🐛 Crashes a lot
- 🐛 Buggy and unstable
- 🐛 Slow and crashes often
- 🐛 Vile trash and unusable
- 🐛 Inaccurate and provides strange responses

**Reported bugs**

- Crashes when downloading larger models
- Shortcuts integration issues
- Conversations get cleared when switching away
- Doesn't work with accessibility features

**Requested features**

- Allow importing own models
- Add chat history and export options
- Implement voice to chat and RAG features
- Add support for larger models on Mac
- Provide more information about each model


## Frequently asked questions

### Is Diffraction Grating Calculator free?

Diffraction Grating Calculator costs $2.99, with no in-app purchases.

### Is Private LLM free?

Private LLM costs $4.99, with no in-app purchases.

### Do Diffraction Grating Calculator or Private LLM have ads?

Neither Diffraction Grating Calculator nor Private LLM shows ads.

### Which is updated more often, Diffraction Grating Calculator or Private LLM?

Diffraction Grating Calculator ships an update every 29 months, and Private LLM every 6 weeks. Most recently, Diffraction Grating Calculator was updated on September 29, 2026 and Private LLM on October 18, 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.*