Comparison

Smart PDF+ Editor vs ARPen

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • Ink annotations
  • Document signing
  • File organization
  • PDF reading
  • Document sharing
Features
Read full description

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

About

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.

Highlights
  • 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
Features
Read full description

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

Smart PDF+ Editor4 screens
ARPen4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 4 months. The most recent releases landed on October 24, 2026 and October 9, 2026 respectively.

Scorecard5 real differences · 5 level
Smart PDF+ Editor versus ARPen: the parameters behind the verdict, then further details
ParameterSmart PDF+ EditorARPen
Price$4.99Free — better
Rating3.8 (53 ratings) — better2.5 (2 ratings)
Positive reviews5.3% of reviews50.0% of reviews — better
Number of ratings53 — better2
Update frequencyEvery 4 monthsEvery 4 months
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS15.614.2 — better
Further details — not scored
Size11 MB55 MB
Age rating4+4+
DeveloperQrayon, LLCRWTH Aachen University

Customer experience

Smart PDF+ Editor

All ratings53 ratings
Positive69.8%
Neutral3.8%
Negative26.4%
Written reviews19 reviews
Positive5.3%
Neutral0.0%
Negative94.7%

ARPen

All ratings2 ratings
Positive50.0%
Neutral0.0%
Negative50.0%
Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

In-app purchases

None

Smart PDF+ Editor

No in-app purchases

None

ARPen

No in-app purchases

Questions

Is Smart PDF+ Editor free?
Smart PDF+ Editor costs $4.99, with no in-app purchases.
Is ARPen free?
ARPen is free to download, with no in-app purchases.
Which has better reviews, Smart PDF+ Editor or ARPen?
Smart PDF+ Editor is rated higher. Smart PDF+ Editor averages 3.8 out of 5 from 53 ratings, while ARPen averages 2.5 from 2 ratings.
Do Smart PDF+ Editor or ARPen have ads?
Neither Smart PDF+ Editor nor ARPen shows ads.
Which is updated more often, Smart PDF+ Editor or ARPen?
Smart PDF+ Editor ships an update every 4 months, and ARPen every 4 months. Most recently, Smart PDF+ Editor was updated on October 24, 2026 and ARPen on October 9, 2026.

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