# Nitro PDF Pro vs knowb4usign

The clearest difference is rating: knowb4usign at 5.0 against Nitro PDF Pro's 3.9. knowb4usign also leads on in-app purchases (none vs 2) and update cadence (every 2 weeks vs every 2 months). Nitro PDF Pro's advantage is ratings volume (161 vs 1). On price, ads and device support there is nothing between them.

Both are free to download. Nitro PDF Pro sells 2 in-app purchases, starting at $19.99 per year. knowb4usign asks for nothing beyond the download.

knowb4usign holds the better App Store score, 5.0 against 3.9. That said, the two scores are not equally well evidenced: Nitro PDF Pro has 161 ratings behind it against 1, so its average is the more settled of the two.

Nitro PDF Pro ships an update every 2 months, knowb4usign every 2 weeks. The most recent releases landed on September 26, 2026 and September 13, 2026 respectively.

## The numbers

| Metric | Nitro PDF Pro | knowb4usign |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.9 (161 ratings)](https://appshunter.io/ios/app/nitro-pdf-pro-read-and-edit/id1608616539/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/knowb4usign/id6779456576/reviews)** |
| Number of ratings | **161** | 1 |
| Positive reviews | 12.5% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 2 weeks** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 59 MB | 23 MB |
| Requires iOS | 18.0 | **15.1** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Nitro Software, Inc.](https://appshunter.io/developer/1607870122) | [Pexora LLC](https://appshunter.io/developer/6779456578) |

## What reviewers say

### Nitro PDF Pro

[App page](https://appshunter.io/ios/app/nitro-pdf-pro-read-and-edit/id1608616539)

Edit, read, sign, and secure PDF documents on your iOS device. This powerful yet lightweight app allows for on-the-go productivity with features like text editing, annotation, form filling, and cloud syncing.

**Highlights:** Edit PDF text, Annotate and highlight PDFs, Fill and save PDF forms, Sign and share PDF documents, Password protect PDFs, Sync with cloud storage, Merge and organize PDFs

**Features:** Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Annual Subscription | $19.99 | per year |
| Nitro PDF Pro for iOS | $9.99 | one-time |

**What reviewers like**

- 👍 Helpful for managing project documents
- 👍 Convenient for PDF modifications
- 👍 Superior PDF handling on Mac
- 👍 Satisfactory in both Mac and Windows environments

**What reviewers complain about**

- 👎 Pro features not available on iOS/iPadOS
- 👎 Yearly charges for basic features
- 👎 Expensive and useless
- 👎 Fails to deliver promised features
- 👎 Impossible to reorder PDF files

**Reported bugs**

- Cannot reorder PDF files
- Crashes when opening PDFs from websites/email
- Does not save markups or documents
- Difficulty creating new folders
- Cannot rotate pages

**Requested features**

- Keyboard support (Cmd + F for search)
- Ability to cancel search with Esc
- OCR and conversion to text documents on tablets
- User manual for iPad app
- Support for Apple Pencil


### knowb4usign

[App page](https://appshunter.io/ios/app/knowb4usign/id6779456576)

This app provides plain-English summaries of legal documents like contracts, leases, and terms of service. It breaks down complex clauses, highlights your obligations and rights, and assigns a risk score for quick understanding. Upload or scan documents for an instant AI review.

**Highlights:** Plain-English contract summaries, Clause-by-clause breakdown, Identification of obligations and rights, Risk assessment score, Document upload and camera scanning, AI-powered review, Follow-up question chat

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Nitro PDF Pro free?

Nitro PDF Pro is free to download, with in-app purchases available.

### Is knowb4usign free?

knowb4usign is free to download, with no in-app purchases.

### Which has better reviews, Nitro PDF Pro or knowb4usign?

knowb4usign is rated higher. Nitro PDF Pro averages 3.9 out of 5 from 161 ratings, while knowb4usign averages 5.0 from 1 ratings.

### Do Nitro PDF Pro or knowb4usign have ads?

Neither Nitro PDF Pro nor knowb4usign shows ads.

### Which is updated more often, Nitro PDF Pro or knowb4usign?

Nitro PDF Pro ships an update every 2 months, and knowb4usign every 2 weeks. Most recently, Nitro PDF Pro was updated on September 26, 2026 and knowb4usign on September 13, 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.*