# Compress PDF vs UnderMB

The clearest difference is update cadence: UnderMB at every 11 days against Compress PDF's every 5 months. UnderMB also leads on monetization model (ad-supported vs free with in-app purchases) and iOS requirement (15.0 vs 18.2). On price, rating, ratings volume and ads there is nothing between them.

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

On the App Store both sit at effectively the same score — 5.0 for Compress PDF against 5.0 for UnderMB. Both are backed by a comparable volume of ratings — 2 and 1 respectively.

Compress PDF ships an update every 5 months, UnderMB every 11 days. The most recent releases landed on November 7, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | Compress PDF | UnderMB |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (2 ratings)](https://appshunter.io/ios/app/compress-pdf-pdf-size-reduce/id6756518223/reviews) | [5.0 (1 ratings)](https://appshunter.io/ios/app/undermb-file-size-compressor/id6811049521/reviews) |
| Number of ratings | **2** | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | Yes | Yes |
| Update frequency | Every 5 months | **Every 11 days** |
| Monetization | Free with in-app purchases | **Ad-supported** |
| Size | 3 MB | 9 MB |
| Requires iOS | 18.2 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Pratik Kadam](https://appshunter.io/developer/1696967727) | [CEMRE SIMSEK](https://appshunter.io/developer/6801148028) |

## What reviewers say

### Compress PDF

[App page](https://appshunter.io/ios/app/compress-pdf-pdf-size-reduce/id6756518223)

This app offers a suite of tools to manage PDF files, including compression to reduce size, merging multiple documents, splitting large files, and extracting text from images. It prioritizes user privacy by processing all files locally on your device.

**Highlights:** Compress PDF files, Merge multiple PDFs, Split PDF documents, OCR text recognition, Reorder and remove pages, Convert images to PDF

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

**In-app purchases:** none


### UnderMB

[App page](https://appshunter.io/ios/app/undermb-file-size-compressor/id6811049521)

Reduce the size of photos, videos, audio, and PDFs on your device. Select a target file size or use presets for common uploads like email or chat apps. Preview your compressed files before saving or sharing, with optional metadata removal.

**Highlights:** Compress images, videos, audio, and PDFs, Choose target file size (KB/MB), Built-in presets for uploads, Preview before saving, Optional metadata removal, Batch processing

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

**In-app purchases:** none


## Frequently asked questions

### Is Compress PDF free?

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

### Is UnderMB free?

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

### Which has better reviews, Compress PDF or UnderMB?

Compress PDF and UnderMB are both rated 5.0 out of 5 on the App Store, from 2 and 1 ratings respectively.

### Do Compress PDF or UnderMB have ads?

Both Compress PDF and UnderMB show ads.

### Which is updated more often, Compress PDF or UnderMB?

Compress PDF ships an update every 5 months, and UnderMB every 11 days. Most recently, Compress PDF was updated on November 7, 2026 and UnderMB on October 31, 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.*