# Smart PDF Compressor vs UnderLimit

The clearest difference is in-app purchases: Smart PDF Compressor at none against UnderLimit's 1. UnderLimit's advantage is update cadence (every 2 days vs every 9 days). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. UnderLimit sells 1 one-off in-app purchase. Smart PDF Compressor asks for nothing beyond the download.

Smart PDF Compressor ships an update every 9 days, UnderLimit every 2 days. The most recent releases landed on October 19, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | Smart PDF Compressor | UnderLimit |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 9 days | **Every 2 days** |
| Size | 2 MB | 4 MB |
| Requires iOS | 18.0 | **17.0** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Quan Dang](https://appshunter.io/developer/1868401962) | [ALESSANDRO VINCENZO DEL BALZO](https://appshunter.io/developer/6813135046) |

## What reviewers say

### Smart PDF Compressor

[App page](https://appshunter.io/ios/app/smart-pdf-compressor-reduce/id6757997785)

**Features:** macOS Compatibility

**In-app purchases:** none


### UnderLimit

[App page](https://appshunter.io/ios/app/underlimit-pdf-compressor/id6813135044)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| UnderLimit Unlimited | $2.99 | one-time |


## Frequently asked questions

### Is Smart PDF Compressor free?

Smart PDF Compressor is free to download, with no in-app purchases.

### Is UnderLimit free?

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

### Do Smart PDF Compressor or UnderLimit have ads?

Neither Smart PDF Compressor nor UnderLimit shows ads.

### Which is updated more often, Smart PDF Compressor or UnderLimit?

Smart PDF Compressor ships an update every 9 days, and UnderLimit every 2 days. Most recently, Smart PDF Compressor was updated on October 19, 2026 and UnderLimit on October 14, 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.*