# SubSum vs Echo IM

The clearest difference is update cadence: Echo IM at weekly against SubSum's every 4 months. SubSum's advantage is iOS requirement (17 vs 26.2). 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.

SubSum ships an update every 4 months, Echo IM weekly. The most recent releases landed on October 12, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | SubSum | Echo IM |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Weekly** |
| Size | 2 MB | 95 MB |
| Requires iOS | **17** | 26.2 |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [桥 汪](https://appshunter.io/developer/1658027527) | [Tadwill & Co., Limited](https://appshunter.io/developer/351931205) |

## What reviewers say

### SubSum

[App page](https://appshunter.io/ios/app/subsum/id6754885566)

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

**In-app purchases:** none


### Echo IM

[App page](https://appshunter.io/ios/app/echo-im/id6757745646)

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

**In-app purchases:** none


## Frequently asked questions

### Is SubSum free?

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

### Is Echo IM free?

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

### Do SubSum or Echo IM have ads?

Neither SubSum nor Echo IM shows ads.

### Which is updated more often, SubSum or Echo IM?

SubSum ships an update every 4 months, and Echo IM weekly. Most recently, SubSum was updated on October 12, 2026 and Echo IM on October 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.*