PDF Viewer by Nutrient vs Los OSOs
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
PDF Viewer by Nutrient
Easily view, search, and annotate PDF documents on your iPhone and iPad. Import files from cloud services, fill out forms, add signatures, and organize your documents. Advanced features like redaction and combining documents are available with a Pro subscription.
- View and search PDFs
- Annotate with highlights and notes
- Sign documents digitally
- Fill out PDF forms
- Organize and share documents
- Import from cloud services
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PDF Viewer is a fast and beautiful app, allowing you to view, search, and annotate PDF documents with ease on your iPhone and iPad. Access your files from iCloud, Dropbox, Box, OneDrive, Google Drive or any other cloud solution via Apple's familiar Document Browser interface. +++ Listed as “Productivity lifesaver” on the App Store +++ "A streamlined interface packed with powerful features - it’s like having a desktop-quality PDF toolkit wherever we go" – App Store Editor Notes “I'm impressed by how the folks at PSPDFKit have been able to fine-tune the document browser to the app's needs.” – MacStories.net "If you want a PDF viewer that is designed for reading PDF books, this is it." – App Review VIEW DOCUMENTS ON THE GO • Easily import a PDF from your favorite cloud service provider, email, or directly off a website. • Supports Open In Place, Drag & Drop and features the familiar Apple Document Browser interface from the Files app. • Search for the exact text you are looking for within the document. • Double tap on the screen to Smart Zoom directly to the text you want to read. • Annotate images (JPEG, PNG) non-destructive, just like PDF documents. (PRO) ANNOTATE WITH EASE • While reviewing a document, use your finger or Apple Pencil to highlight and markup text. • Leave comments by adding a note, text, or drawing directly on the PDF. • Add images or audio. • Reply to notes. (PRO) SIGN DOCUMENTS ANYWHERE • Add your signature to any document using your finger or Apple Pencil. • Move and resize your signature as needed. • Flatten a document to ensure the signature doesn’t change. CREATE AND EDIT PDFs • Create new documents from existing documents by moving, rotating, deleting, or adding new pages. • Combine multiple documents into a single one. (PRO) • Add bookmarks to easily return to certain pages in large documents. FILL OUT FORMS • Quickly fill out PDF Forms by adding text to the fields. • Flatten and secure the form once you’re done to ensure the document doesn’t change. • Add a signature to any Form. STORE, ORGANIZE AND SHARE • Store documents, create folders and organize your documents. • Share documents by printing, emailing or saving your edits back any cloud service. PASSWORD PROTECT DOCUMENTS • Read document metadata, title and keywords. • Protect documents with user and owner passwords and limit permissions. (PRO) AND SO MUCH MORE • Conveniently switch to night mode when viewing your documents at night. • Present on external screens without the distraction of toolbars. (PRO) • Have the text from a PDF read out loud to you with text-to-speech. • PDF Viewer remembers where you were down to the page/position where you left off - even across devices. PRICING PDF Viewer comes with a large feature set, completely free. Some advanced features require the purchase of PDF Viewer Pro, available as a subscription. We offer 3-monthly and yearly subscription plans. There’s also a fully functional 7-day trial, so you can test PDF Viewer Pro (including document merging and password editing) before you commit. All plans unlock the app on iPhone and iPad. TRUSTED BY COMPANIES YOU KNOW PDF Viewer is built on top of and powered by PSPDFKit, the same PDF engine trusted around the world by companies like Dropbox, Box, IBM, Atlassian, SAP, and Lufthansa. BE PART OF THE PDF VIEWER COMMUNITY pdfviewer.io twitter.com/pdfviewerapp LEGAL Duration and price of each subscription are displayed in PDF Viewers’ storefront, updated at the time of purchase. Payment will be charged to iTunes account at confirmation of purchase. Subscriptions automatically renew unless auto-renew is turned off no later than 24 hours before the end of the current period. Subscriptions and auto-renewal can be managed/turned off in the iTunes account settings. Any unused portion of a free trial period is forfeited as soon as a subscription is purchased. Terms of Use: https://pdfviewer.io/terms Privacy Policy: https://pdfviewer.io/privacy
Los OSOs
This app helps you understand and express your emotions through a unique, non-verbal system. Record and share your sentiment over time to improve self-awareness, leadership, and teamwork. Designed with an elegant and intuitive interface.
- Non-verbal sentiment recording
- 3D emotion tracking (Happiness, Energy, Assuredness)
- Sentiment sharing for teamwork
- Elegant and intuitive design
- Personal sentiment review over time
- Proprietary OSO-Pearl technology
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Amplify your sentiment to maximize your potentials! Practicing the awareness of your sentiment is an important life skill. Recording and sharing your sentiment for your own review over time as well as sharing your sentiment with others improve your leadership goals and team work successes. If you find yourself resonating with the above, and you also appreciate natural & elegant designs, Los OSOs is the App for you. Some Frequently Asked Questions (FAQs) to orient you better: (1) How can I conceptualize the Los OSOs App? Think of your Los OSOs App as your sentiment GPS. (2) What is unique about Los OSOs in terms of recording sentiment? Importantly, Los OSOs offers a way to record and share your sentiment without involving language (i.e., words) (see FAQs #6 & #6 below for more about the OSO-Pearl technology). Los OSOs is designed to be easy to use, quick, and elegant. (3) Where does the name OSO come from? Our app and technology is affectionately named OSO, meaning bear in Spanish and pays tribute to Cloudbear - our Great Pyrenees dog and beloved family member and livestock guardian - known for his boundless love and vigilance against predators. Our Spanish speaking friends call Cloudbear “oso” given his striking resemblance to a polar bear. Cloudbear has a big heart, he readily shares his sentiment constantly, so it is very fitting that our OSO Apps are named after him. (4) What is the technology behind the Los OSOs App? The Los OSOs App is powered by the new and proprietary OSO-Pearl technology from the KRONxArc / Nectelier Team. (5) How does the OSO-Pearl Technology work? Touch the OSO-Pearl interactive area to record your emotion in 3 dimensions: x, y, and z, for happiness (H), energy (E), and assuredness (A), respectively. For example, if you feel happy, your OSO Mark would be on the right half of the OSO-Pearl because that's the "+" side of the x-axis; if you feel your energy is elevated, your OSO Mark would be on the top half of the OSO-Pearl because that's the "+" side of the y-axis; if you're very sure about how you feel, tap multiple times to mark your OSO to express your certainty - this increases your assuredness which is the z-axis value. (6) What is the lexicon of the Los OSOs App? When using the Los OSOs App, we think of the word 'OSO' as a noun, verb, or an adjective. For example, capturing a sentiment with the Los OSOs App can be described as creating an OSO. The action of engaging with the App is called OSO-ing. The OSO also refers to the interactive area that resembles a pearl. Your creation, i.e., the OSO-Pearl with the "OSO Mark" that you'll have marked is called your OSO. Imagine thinking or asking "How's your OSO?" as a way to show you care and recording your sentiment. When a topic or subject (words, phrase, image, etc.) has been OSO'ed by someone, it shows this subject is worthy of being OSO'ed and worthy of the user's time and efforts. (7) What's the difference between Los OSOs App and OSO+ App? Los OSOs App is designed to be shared with your team and the community to improve team work, leadership, and business product ratings type applications. OSO+ App (a sister-app in the OSO App family) is designed primarily for private personal use. (8) How about my data privacy? The Los OSOs App is designed for sharing your sentiments. Importantly, your data is not linked to you, so your anonymity is maintained. When you OSO with the Los OSOs App, the data is shared with our database. (9) Where can I find App Terms of Use, Privacy Policy, Tutorials and more? We follow the Apple standard Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Check out our website http://www.kronarc.com/oso for more as well as links on our website to video tutorials our team has created. (10) How can I reach the Los OSOs App team? User requests and feedbacks are our priority - reach us via support@kronarc.com Time to start OSO-ing, enjoy!
Screenshots
Verdict
The clearest difference is price: PDF Viewer by Nutrient at Free against Los OSOs's $2.99. PDF Viewer by Nutrient also leads on ratings volume (9.1K vs 1) and device support (4 vs 2). Los OSOs's advantage is rating (5.0 vs 4.6) and review sentiment (100% vs 73%). On ads, in-app purchases and iOS requirement 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
PDF Viewer by Nutrient is free to download; Los OSOs costs $2.99 up front. PDF Viewer by Nutrient sells 2 in-app purchases, starting at $6.99 per 3 months and Los OSOs sells 2 in-app purchases, starting at $9.99 per month. Whichever you choose, the download price is not the number that matters.
Los OSOs holds the better App Store score, 5.0 against 4.6. That said, the two scores are not equally well evidenced: PDF Viewer by Nutrient has 9.1K ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 73% of PDF Viewer by Nutrient's written reviews are positive against 100% of Los OSOs's.
PDF Viewer by Nutrient ships an update monthly, Los OSOs every 6 days. The most recent releases landed on October 27, 2026 and October 24, 2026 respectively.
| Parameter | PDF Viewer by Nutrient | Los OSOs |
|---|---|---|
| Price | Free — better | $2.99 |
| Rating | 4.6 (9.1K ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 73.3% of reviews | 100.0% of reviews — better |
| Number of ratings | 9.1K — better | 1 |
| Update frequency | Monthly | Every 6 days — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Freemium — better | Paid |
| Devices | iPhone, iPad, Mac, Vision Pro — better | iPhone, Apple Watch |
| Requires iOS | 17.0 | 16.2 — better |
| Further details — not scored | ||
| Size | 109 MB | 282 MB |
| Age rating | 4+ | 17+ |
| Developer | PSPDFKit GmbH | Nectelier Inc. |
Customer experience
PDF Viewer by Nutrient
Los OSOs
Bugs and requests
PDF Viewer by Nutrient
Reported bugs
4 issues- Annotations randomly disappearing or not saving
- Incompatibility issues with certain PDF files
- Scrolling and panning problems on large PDFs
- Unexpected crashes after iOS updates
Requested features
5 requests- Add a rubber/eraser tool for annotations
- Implement a side-by-side PDF view mode
- Improve palm rejection and gesture support
- Allow customization of toolbar and shortcuts
- Provide better options for PDF file management
Los OSOs
Not enough reviews yet to summarise bugs or requests.
In-app purchases
PDF Viewer by Nutrient
- PDF Viewer Pro 3 Months7 Days trial$6.993 Months
- PDF Viewer Pro Yearly7 Days trial$19.991 Year
Los OSOs
- Los OSO Monthly$9.991 Month
- Los OSO Yearly$83.001 Year







