# iTurbo vs BiLibre DjVu and PDF Reader

The clearest difference is price: iTurbo at Free against BiLibre DjVu and PDF Reader's $1.99. iTurbo also leads on rating (5.0 vs 4.3). BiLibre DjVu and PDF Reader's advantage is update cadence (every 10 days vs every 54 months) and ratings volume (103 vs 1). On ads, in-app purchases and device support there is nothing between them.

iTurbo is free to download; BiLibre DjVu and PDF Reader costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

iTurbo holds the better App Store score, 5.0 against 4.3. That said, the two scores are not equally well evidenced: BiLibre DjVu and PDF Reader has 103 ratings behind it against 1, so its average is the more settled of the two.

iTurbo ships an update every 54 months, BiLibre DjVu and PDF Reader every 10 days. The most recent releases landed on October 14, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | iTurbo | BiLibre DjVu and PDF Reader |
| --- | --- | --- |
| Price | **Free** | $1.99 |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/iturbo/id314368331/reviews)** | [4.3 (103 ratings)](https://appshunter.io/ios/app/bilibre-djvu-and-pdf-reader/id1230039040/reviews) |
| Number of ratings | 1 | **103** |
| Positive reviews | — | 41.1% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 54 months | **Every 10 days** |
| Monetization | **Free** | Paid |
| Best chart rank | — | **#190** |
| Size | 2 MB | 57 MB |
| Requires iOS | 18.0 | **10.0** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 17+ |
| Developer | [ManneTroll Solutions](https://appshunter.io/developer/313743954) | [Konstantin Bukreev](https://appshunter.io/developer/547576207) |

## What reviewers say

### iTurbo

[App page](https://appshunter.io/ios/app/iturbo/id314368331)

This app simulates fluid dynamics by solving Navier-Stokes equations for 2D incompressible turbulence. It uses a direct numerical simulation method with Euler time stepping and Fourier space calculations for efficiency.

**Highlights:** Direct Numerical Simulation (DNS), Navier-Stokes equation solver, 2D incompressible turbulence, Euler time stepping, Fourier space calculations, Vorticity field transformation

**Features:** macOS Compatibility

**In-app purchases:** none


### BiLibre DjVu and PDF Reader

[App page](https://appshunter.io/ios/app/bilibre-djvu-and-pdf-reader/id1230039040)

**Currently charting:** #190 Top Paid · Education (US App Store)

Read and organize technical, scientific, and educational literature in DjVu and PDF formats. Features include customizable reading modes, powerful annotation tools, a built-in summary editor, and advanced DjVu processing. Manage your library with smart cataloging and metadata editing.

**Highlights:** Customizable reading modes, Annotation and drawing tools, Summary editor with Markdown, DjVu text recognition, Full text searching, Library cataloging and metadata editing, Cloud synchronization

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is iTurbo free?

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

### Is BiLibre DjVu and PDF Reader free?

BiLibre DjVu and PDF Reader costs $1.99, with no in-app purchases.

### Which has better reviews, iTurbo or BiLibre DjVu and PDF Reader?

iTurbo is rated higher. iTurbo averages 5.0 out of 5 from 1 ratings, while BiLibre DjVu and PDF Reader averages 4.3 from 103 ratings.

### Do iTurbo or BiLibre DjVu and PDF Reader have ads?

Neither iTurbo nor BiLibre DjVu and PDF Reader shows ads.

### Which is updated more often, iTurbo or BiLibre DjVu and PDF Reader?

iTurbo ships an update every 54 months, and BiLibre DjVu and PDF Reader every 10 days. Most recently, iTurbo was updated on October 14, 2026 and BiLibre DjVu and PDF Reader on October 24, 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.*