# uSpectrum MK350D vs Inbox Zero

The clearest difference is in-app purchases: uSpectrum MK350D at none against Inbox Zero's 2. uSpectrum MK350D also leads on iOS requirement (8.0 vs 18.0). Inbox Zero's advantage is update cadence (weekly vs every 2 months). On price, ads and device support there is nothing between them.

Both are free to download. Inbox Zero sells 2 in-app purchases, starting at $19.99 per month. uSpectrum MK350D asks for nothing beyond the download.

uSpectrum MK350D ships an update every 2 months, Inbox Zero weekly. Both last shipped on October 24, 2026.

## The numbers

| Metric | uSpectrum MK350D | Inbox Zero |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.0 (2 ratings)](https://appshunter.io/ios/app/uspectrum-mk350d/id876342072/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Weekly** |
| Monetization | **Free** | Subscription |
| Size | 39 MB | 35 MB |
| Requires iOS | **8.0** | 18.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [United Power Research Technology Corporation](https://appshunter.io/developer/1501316337) | [Inbox Zero Inc.](https://appshunter.io/developer/1880462164) |

## What reviewers say

### uSpectrum MK350D

[App page](https://appshunter.io/ios/app/uspectrum-mk350d/id876342072)

This portable spectrometer offers easy-to-use lighting analysis for production environments. It features BLE remote control and SD card data storage for efficient workflow and advanced light analytics.

**Highlights:** BLE remote control, SD card data storage, Fast lighting readings, Advanced light analytics, Efficient workflow features

**Features:** macOS Compatibility

**In-app purchases:** none


### Inbox Zero

[App page](https://appshunter.io/ios/app/inbox-zero-ai-email-assistant/id6759736561)

This AI-powered assistant helps you manage your email inbox efficiently. It prioritizes important messages, drafts replies in your style, and helps you unsubscribe from unwanted newsletters. Automate email handling with custom rules and stay in control of your communications.

**Highlights:** Prioritize important emails, Draft AI-assisted replies, Unsubscribe from newsletters, Bulk archive emails, Create custom automation rules, Manage multiple Gmail accounts

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Inbox Zero Starter Monthly | $19.99 | per month |
| Inbox Zero Starter Annual | $199.99 | per year |


## Frequently asked questions

### Is uSpectrum MK350D free?

uSpectrum MK350D is free to download, with no in-app purchases.

### Is Inbox Zero free?

Inbox Zero is free to download, with in-app purchases available.

### Do uSpectrum MK350D or Inbox Zero have ads?

Neither uSpectrum MK350D nor Inbox Zero shows ads.

### Which is updated more often, uSpectrum MK350D or Inbox Zero?

uSpectrum MK350D ships an update every 2 months, and Inbox Zero weekly. Most recently, uSpectrum MK350D was updated on October 24, 2026 and Inbox Zero on October 24, 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.*