# SIGMA vs PDF Converter

The clearest difference is in-app purchases: SIGMA at none against PDF Converter's 2. SIGMA also leads on ads (none vs shown) and iOS requirement (13.0 vs 15.6). On price, update cadence and device support there is nothing between them.

Both are free to download. PDF Converter sells 2 in-app purchases, starting at $5.99 per 7 days. SIGMA asks for nothing beyond the download.

SIGMA ships an update monthly, PDF Converter every 2 weeks. The most recent releases landed on September 5, 2026 and September 21, 2026 respectively.

## The numbers

| Metric | SIGMA | PDF Converter |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.7 (22 ratings)](https://appshunter.io/ios/app/pdf-converter-ocr-reader/id6758373190/reviews)** |
| Number of ratings | — | **22** |
| Positive reviews | — | 18.2% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Monthly | **Every 2 weeks** |
| Monetization | — | Free with in-app purchases |
| Size | 25 MB | 93 MB |
| Requires iOS | **13.0** | 15.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Turker KAYALIOLU](https://appshunter.io/developer/1851236946) | [Hitek Limited](https://appshunter.io/developer/6774064976) |

## What reviewers say

### SIGMA

[App page](https://appshunter.io/ios/app/sigma/id6754983866)

**Features:** macOS Compatibility

**In-app purchases:** none


### PDF Converter

[App page](https://appshunter.io/ios/app/pdf-converter-ocr-reader/id6758373190)

Effortlessly transform paper documents into digital files with scanning, text recognition, and editing tools. Ideal for students, professionals, and everyday users needing to organize and manage documents.

**Highlights:** Photo scanning to digital files, OCR text recognition and copying, Import and view local PDFs, Page management (delete, rearrange), Highlighting and annotation tools, Intuitive user interface

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| PDF Converter Ad-Free | $5.99 | per 7 days |
| PDF Converter Ad-Free | $29.99 | per year |


## Frequently asked questions

### Is SIGMA free?

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

### Is PDF Converter free?

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

### Do SIGMA or PDF Converter have ads?

PDF Converter shows ads; SIGMA does not.

### Which is updated more often, SIGMA or PDF Converter?

SIGMA ships an update monthly, and PDF Converter every 2 weeks. Most recently, SIGMA was updated on September 5, 2026 and PDF Converter on September 21, 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.*