
Which is more popular?
Based on our record, Okular seems to be more popular. It has been mentioned 44 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | okular.kde.org | opalstack.com |
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What each product offers, as listed by its team.


Possible disadvantages
Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
Okular is recommended for students, educators, professionals, and any users who require a reliable and feature-rich document viewer capable of handling a wide range of file formats. It is particularly beneficial for those who value open-source software and need robust annotation and document management tools across different platforms.
Overall verdict
Why this product is good
Recommended for
Walkthroughs and reviews on video.
How often each product is chosen within a category, 0–100% relative to the other.


Share your experience with using Okular and Opalstack. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


Verdict: Okular is an open source and can be used free, which is probably its main advantage. At the same time, its basic functionality is meant to be not only highly competitive with PDF Expert but rather overcomes...
Okular is another open-source and cross-platform document viewer developed by KDE and is shipped as part of the KDE Application release.
We have no reviews of Opalstack yet. Be the first one to post
Recommendations tracked on public social media and blogs since March 2021.


If you mean signing as in "signing with your handwritten signature", you could use Okular () which easily allows you to do that. Filling out forms also works nicely. Source: almost 3 years ago
I was in a similar position lately until I found Okular. Have you tried it? https://okular.kde.org/. - Source: Hacker News / about 3 years ago
I would try Okular first, though, which is free and open source: https://okular.kde.org/. Source: about 3 years ago
Tracking Opalstack since Sep 2023.
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