# PDFOptim vs Cenntrum

The clearest difference is in-app purchases: Cenntrum at none against PDFOptim's 3. Cenntrum also leads on update cadence (every 4 days vs every 5 months) and review sentiment (100% vs 76%). PDFOptim's advantage is ratings volume (295 vs 2). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. PDFOptim sells 3 in-app purchases, starting at $0.99 per month. Cenntrum asks for nothing beyond the download.

Cenntrum holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: PDFOptim has 295 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 76% of PDFOptim's written reviews are positive against 100% of Cenntrum's.

PDFOptim ships an update every 5 months, Cenntrum every 4 days. The most recent releases landed on November 11, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | PDFOptim | Cenntrum |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.7 (295 ratings)](https://appshunter.io/ios/app/pdfoptim/id903356489/reviews) | **[5.0 (2 ratings)](https://appshunter.io/ios/app/cenntrum/id6449678687/reviews)** |
| Number of ratings | **295** | 2 |
| Positive reviews | 75.6% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 5 months | **Every 4 days** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 8 MB | 87 MB |
| Requires iOS | 15.6 | **15.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 17+ |
| Developer | [RootRise Technologies Pvt. Ltd.](https://appshunter.io/developer/594431033) | [Aquiles Gatas](https://appshunter.io/developer/1690039483) |

## What reviewers say

### PDFOptim

[App page](https://appshunter.io/ios/app/pdfoptim/id903356489)

Easily compress and optimize PDF files on your iPhone and iPad. Reduce the size of large documents, saving storage space and transmission time. Offers both automatic and manual compression modes with advanced settings for image and vector graphics.

**Highlights:** Compress PDF documents, Optimize PDF files, Automatic compression mode, Manual compression mode, Adjust image resolution and quality, Optimize vector graphics, Support for password-protected PDFs

**Features:** Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium : Monthly Access | $0.99 | per month |
| Premium : Yearly Access | $2.99 | per year |
| Premium : Lifetime Access | $4.99 | one-time |

**What reviewers like**

- 👍 Excellent compression quality
- 🚀 Efficient and fast performance
- 👍 Simple and easy to use
- 💰 Good value for money (one-time purchase)
- 👍 No annoying subscriptions

**What reviewers complain about**

- 🐛 App not launching/freezing
- 🐛 Doesn't work for certain file types (e.g., GoodNotes)
- 🐛 Poor image quality/pixelation
- 🐛 Compression not effective on all PDFs
- 🐛 Confusing or illogical interface

**Reported bugs**

- App not launching on iOS 18.0.1
- App freezes during launch
- App won't take purchases
- Cannot optimize certain PDFs
- Compression not effective on marked-up PDFs

**Requested features**

- Support for iOS shortcuts
- macOS version integration/cross-platform compatibility
- Improved handling of specific file types like GoodNotes
- Better optimization for handwritten notes within PDFs
- Cloud storage for compressed documents (iCloud)


### Cenntrum

[App page](https://appshunter.io/ios/app/cenntrum/id6449678687)

This app encourages users to avoid phone use while driving by offering rewards. It aims to improve road safety and promote a more engaged life beyond the screen.

**Highlights:** Rewards for not using phone while driving, Promotes road safety, Encourages engagement with life, Reduces phone distraction

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is PDFOptim free?

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

### Is Cenntrum free?

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

### Which has better reviews, PDFOptim or Cenntrum?

Cenntrum is rated higher. PDFOptim averages 4.7 out of 5 from 295 ratings, while Cenntrum averages 5.0 from 2 ratings.

### Do PDFOptim or Cenntrum have ads?

Neither PDFOptim nor Cenntrum shows ads.

### Which is updated more often, PDFOptim or Cenntrum?

PDFOptim ships an update every 5 months, and Cenntrum every 4 days. Most recently, PDFOptim was updated on November 11, 2026 and Cenntrum on November 3, 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.*