Comparison

Diffraction Grating Calculator vs Private LLM

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

Head to head
About

Diffraction Grating Calculator

Features
Read full description

Diffraction Grating Calculator is a physics/math calculator that calculates the angles of diffracted orders of monochromatic light when shone on a reflective diffraction grating. Features: - Instant calculation. - Results are copyable to other apps. - Formulas are included as reference. - Supports up to 16 decimal places. - Supports various units for each input. - Works seamlessly on both iPhone and iPad. - Lightweight, compact app optimized for everyday use. - Ad-free and built with privacy in mind. In optics, a diffraction grating is an optical component with a periodic structure that splits and diffracts light into several beams traveling in different directions. The emerging coloration is a form of structural coloration. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element. Because of this, gratings are commonly used in monochromators and spectrometers. A diffraction grating is a material that contains a large number of parallel slits separated by a distance (d). This periodic separation of slits is usually on the order of micrometers. Because this distance is on the order of the wavelength of light, when light waves pass through the grating, the slits are able to cause constructive and destructive interference among the light waves. The waves will constructively interfere if the angle of reflection delays one of the waves by a whole wavelength. Diffraction grating equation: m * λ = a * sin(θm) Where: m: The order number of the diffracted image, m = 1,2,3 ... θ: Grating angle, in radians a: Grating Spacing, in lines per meter λ: Wavelength, in meters Thanks for your support and do visit nitrio.com for more apps for your iOS devices.

About

Private LLM

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
Read full description

Discover the Ultimate Privacy-Focused AI Assistant on iOS: Private LLM Unlock a new realm of productivity and creativity on your iPhone and iPad with Private LLM, the premier AI assistant designed with your privacy in mind. Available for a one-time purchase, it offers a range of AI capabilities without needing a subscription. Experience advanced on-device AI that keeps your interactions confidential and offline. Why Private LLM is Your Go-To AI Companion: - Exclusive AI Model Selection: Choose from a diverse set of open-source LLM models optimized for performance and perplexity on iOS with state of the art OmniQuant quantization: including models from Llama 2, Llama 3.2, Llama 3.1, Google Gemma 2, Gemma 3, Microsoft Phi-3, Mistral 7B, Qwen 2.5, Qwen 3, StableLM 3B and many more. Whether you need help with creative brainstorming, coding, or daily questions, customize your AI experience to meet your unique needs. - Integrated with Siri & Shortcuts: Enhance your AI interactions with Siri commands and customizable Shortcuts. Private LLM seamlessly fits within your Apple ecosystem, making your digital assistant more accessible. - Customizable Interactions: Tailor your AI's responses and interactions with customizable system prompts to match your preferences and needs. - Uncompromised Privacy and Security: With Private LLM, your conversations stay confidential and on your device. Our advanced on-device AI performs robust computing without risking data compromise or needing an internet connection. - Family Sharing & Offline Capabilities: Benefit from a one-time purchase that includes Family Sharing. Download models as needed and enjoy the full functionality of your AI assistant, even without internet access. Supported LLM Model families: - DeepSeek R1 Distill based models - Phi 4 based models - Qwen 3 based models (Qwen3-4B-Instruct-2507) - Qwen 2.5 based models (0.5B, 1.5B, 3B and 7B) - Qwen 2.5 Coder based Models (0.5B, 1.5B, 3B, 7B and 14B) - Llama 3.1 8B based models - Llama 3.2 1B and 3B based models - Google Gemma 2 2B and 9B based models - Google Gemma 3 1B based models - Mistral 7B based models - Yi 6B based models For a full list of supported models, including detailed specifications, please visit privatellm.app/models. Private LLM is not just a chatbot; it's a comprehensive AI companion designed to respect your privacy while providing versatile, on-demand assistance. Whether you're enhancing your creative writing, tackling complex programming challenges, or just seeking answers, Private LLM adapts to meet your needs while keeping your data secure. Start your journey with Private LLM today and elevate your productivity and creative projects with the most private AI assistant for iOS devices. Private LLM is a better alternative to generic llama.cpp and MLX wrappers apps like Enchanted, Ollama, LLM Farm, LM Studio, Locally AI, RecurseChat, etc on three fronts: 1. Private LLM uses a faster and highly-optimized mlc-llm based inference engine. 2. Models in Private LLM are quantized using the state of the art quantization algorithms like OmniQuant, while competing apps use naive round-to-nearest quantization. 3. Private LLM is a fully native app built using C++, Metal and Swift with deep integrations with iOS and iPadOS, while many of the competing apps are bloated and non-native Electron or Flutter based apps. Please note that Private LLM only supports inference with text based LLMs. Model support varies by device capabilities.

Screenshots

Diffraction Grating Calculator4 screens
Private LLM4 screens

Verdict

The call

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 (#22 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.

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

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.

UpkeepUpdate frequency

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.

Scorecard4 real differences · 7 level
Diffraction Grating Calculator versus Private LLM: the parameters behind the verdict, then further details
ParameterDiffraction Grating CalculatorPrivate LLM
Price$2.99 — better$4.99
Rating—4.2 (719 ratings) — better
Positive reviews—48.7% of reviews
Number of ratings—719 — better
Update frequencyEvery 29 monthsEvery 6 weeks — better
AdsNoNo
In-app purchasesNoNo
Monetization—Paid
Best chart rank—#22 — better
DevicesiPhone, iPad, iPodiPhone, iPad, Mac
Requires iOS13 — better17.0
Further details — not scored
Size1 MB1.3 GB
Age rating4+12+
DeveloperNitrioNumen Technologies Limited

Bugs and requests

Diffraction Grating Calculator

Not enough reviews yet to summarise bugs or requests.

Private LLM

Reported bugs

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

Requested features

7 requests
  • 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
Show 2 more
  • Allow creating custom prompt presets
  • Integrate with iOS Shortcuts

In-app purchases

None

Diffraction Grating Calculator

No in-app purchases

None

Private LLM

No in-app purchases

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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