Smart PDF+ Editor vs ARPen
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Smart PDF+ Editor
This app allows users to read, sign, and annotate PDF documents, especially with stylus input. It's designed for professionals to quickly handle documents and for students to take notes on study materials. Features include a built-in file manager for organization.
- Ink annotations
- Document signing
- File organization
- PDF reading
- Document sharing
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Smart PDF is a PDF editor specially optimized for ink annotations. Use it with an Apple Pencil for the ultimate ease in note taking. Great for professionals Quickly sign and send documents. Review, annotate and share files with your colleagues. Great for students If you spend a lot of time reading and studying documents on your iPad, then Smart PDF is an indispensable tool for getting the most out of your study time. Take notes on documents in class, or while studying at home. Keep all your files organized with the built-in file manager, with color-coded categories. We hope you enjoy Smart PDF! -- The App Makers @ Qrayon
ARPen
Create 3D drawings and models in mid-air using a marker or a custom Bluetooth pen. Explore advanced geometry creation, object manipulation, and depth visualization. Export your creations as STL files.
- Draw freehand in mid-air
- Create simple and complex geometries
- Manipulate objects in 3D space
- Explore depth visualization
- Export models as STL files
- Use marker or custom Bluetooth pen
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The ARPen application enables you to draw in mid-air. By tracking a marker, lines can be created that keep their position in the real world. Printing out a marker is all that is needed to test out this interaction. Or you can build a custom Bluetooth pen to have more options. The pen can be built using simple electronic components and machinery in your local Fab Lab. Detailed instructions are available at http://hci.ac/arpen-ios. With this app you can: - paint freehand in mid-air - create simple geometry shapes like cubes - create complex geometries using sweeps, lofts, revolutions, and merge&intersect operations - explore techniques for moving, rotating, and scaling objects in mid-air - explore different menu techniques - explore depth visualization techniques to show the position of the pen tip relative to other objects in the scene - export the sketch or model as an *.STL file This application is part of the Personal Photonics project, which is funded by the German Federal Ministry of Education and Research (BMBF) as part of their Open Photonics call. For more information, visit https://hci.rwth-aachen.de/arpen
Screenshots
Verdict
The clearest difference is price: ARPen at Free against Smart PDF+ Editor's $4.99. ARPen also leads on review sentiment (50% vs 5%). Smart PDF+ Editor's advantage is rating (3.8 vs 2.5) and ratings volume (53 vs 2). On update cadence, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
ARPen is free to download; Smart PDF+ Editor costs $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Smart PDF+ Editor holds the better App Store score, 3.8 against 2.5. That said, the two scores are not equally well evidenced: Smart PDF+ Editor has 53 ratings behind it against 2, so its average is the more settled of the two. Written reviews complicate that: 5% of Smart PDF+ Editor's written reviews are positive against 50% of ARPen's, so the app with the better star average is not the one people write more warmly about.
Both ship on a similar rhythm, roughly every 4 months. The most recent releases landed on October 24, 2026 and October 9, 2026 respectively.
| Parameter | Smart PDF+ Editor | ARPen |
|---|---|---|
| Price | $4.99 | Free — better |
| Rating | 3.8 (53 ratings) — better | 2.5 (2 ratings) |
| Positive reviews | 5.3% of reviews | 50.0% of reviews — better |
| Number of ratings | 53 — better | 2 |
| Update frequency | Every 4 months | Every 4 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 15.6 | 14.2 — better |
| Further details — not scored | ||
| Size | 11 MB | 55 MB |
| Age rating | 4+ | 4+ |
| Developer | Qrayon, LLC | RWTH Aachen University |
Customer experience
Smart PDF+ Editor
ARPen
In-app purchases
Smart PDF+ Editor
No in-app purchases
ARPen
No in-app purchases









