# MSR Mail Tracker vs Naval Letter Builder

The clearest difference is update cadence: Naval Letter Builder at every 6 days against MSR Mail Tracker's every 3 months. MSR Mail Tracker's advantage is iOS requirement (11.0 vs 17.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

MSR Mail Tracker ships an update every 3 months, Naval Letter Builder every 6 days. The most recent releases landed on September 6, 2026 and September 10, 2026 respectively.

## The numbers

| Metric | MSR Mail Tracker | Naval Letter Builder |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 6 days** |
| Size | 21 MB | 11 MB |
| Requires iOS | **11.0** | 17.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [TRACKEX LLC](https://appshunter.io/developer/1492982032) | [RoxyKovu LLC](https://appshunter.io/developer/1816071699) |

## What reviewers say

### MSR Mail Tracker

[App page](https://appshunter.io/ios/app/msr-mail-tracker/id6449599992)

**Features:** macOS Compatibility

**In-app purchases:** none


### Naval Letter Builder

[App page](https://appshunter.io/ios/app/naval-letter-builder/id6768153774)

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

**In-app purchases:** none


## Frequently asked questions

### Is MSR Mail Tracker free?

MSR Mail Tracker is free to download, with no in-app purchases.

### Is Naval Letter Builder free?

Naval Letter Builder is free to download, with no in-app purchases.

### Do MSR Mail Tracker or Naval Letter Builder have ads?

Neither MSR Mail Tracker nor Naval Letter Builder shows ads.

### Which is updated more often, MSR Mail Tracker or Naval Letter Builder?

MSR Mail Tracker ships an update every 3 months, and Naval Letter Builder every 6 days. Most recently, MSR Mail Tracker was updated on September 6, 2026 and Naval Letter Builder on September 10, 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.*