# 书非借 vs SubSum

The clearest difference is update cadence: 书非借 at every 2 days against SubSum's every 4 months. 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.

书非借 ships an update every 2 days, SubSum every 4 months. The most recent releases landed on October 9, 2026 and October 12, 2026 respectively.

## The numbers

| Metric | 书非借 | SubSum |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 days** | Every 4 months |
| Size | 6 MB | 2 MB |
| Requires iOS | 17.6 | **17** |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [杭州引力网络技术有限公司](https://appshunter.io/developer/1133518651) | [桥 汪](https://appshunter.io/developer/1658027527) |

## What reviewers say

### 书非借

[App page](https://appshunter.io/ios/app/id6741096319)

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

**In-app purchases:** none


### SubSum

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

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

**In-app purchases:** none


## Frequently asked questions

### Is 书非借 free?

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

### Is SubSum free?

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

### Do 书非借 or SubSum have ads?

Neither 书非借 nor SubSum shows ads.

### Which is updated more often, 书非借 or SubSum?

书非借 ships an update every 2 days, and SubSum every 4 months. Most recently, 书非借 was updated on October 9, 2026 and SubSum on October 12, 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.*