Comparison

PDF Viewer by Nutrient vs calmdocs

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

Head to head
About

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.

Highlights
  • View and search PDFs
  • Annotate with highlights and notes
  • Sign documents digitally
  • Fill out PDF forms
  • Organize and share documents
  • Import from cloud services
Features
Read full description

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

About

calmdocs

Features
Read full description

calmdocs is file storage you control. Every save is kept and restorable, every deleted file recoverable, and everything comes back out whenever you want it — a folder as a single zip, or the whole account through a documented API. Files live in named groups on Mac, iPhone, iPad and the web, and photographs can be browsed by date, by place, or at random. No subscription, no advertising, and nothing collected that the app does not need to work. GROUPS Separate libraries, each with its own folder tree: Photos, Work, the scans, the house. You work in one group at a time rather than in a single combined drive. VERSION HISTORY Every save is kept. Open a file's history and restore any earlier version. Restoring does not discard the current one. DELETED FILES Deleting moves a file to the group's bin, not off the server. Restore it at any time. A group can also empty its own bin automatically after a set number of days. PHOTO VIEWS A group can show you: • a random photograph • the most recent • one taken on this day in an earlier year • one from this month • one taken near your current location A slideshow runs any of these full screen and keeps the display awake. PHOTO FILTERING Screenshots, photographs of documents, and blurred or badly exposed shots are excluded from the random, recent and slideshow views. This is always on and applies to every photo view. WIDGETS Home Screen, Lock Screen and StandBy widgets show photographs from a group you choose. Long-press and choose Edit Widget to change the group; two widgets can show two different groups. Tapping one opens the slideshow. A widget can read only the group it shows, and never has your sign-in. Signing out stops them. FILES OF EVERY KIND Photographs, video, audio and PDFs open in the app. Large video is converted for streaming rather than downloaded whole. Any folder can be downloaded as a single zip, and a link to that zip works for someone without the app. SEARCH By name and path, within a group. You can also browse the folder tree or list what changed most recently. ON THE MAC A menu bar app, downloaded from calmdocs.com rather than the App Store, syncs chosen folders on your disk with a group and updates itself. It is not sandboxed, which is what lets it sync folders you choose. ON THE WEB, AND FROM YOUR OWN CODE Everything is also at calmdocs.com in a browser, on the same account. There is a documented HTTP API with an OpenAPI description at calmdocs.com/api/docs. SIGNING IN An email address and a six-digit code. There is no password to reuse, leak or reset. WHAT WE HOLD Your email address, the files you upload, and what those files say about themselves: size, type, when they were taken, and for photographs the position the camera recorded. That is what the service runs on. We do not sell it and we do not track you between apps. The full policy is at calmdocs.com/privacy.

Screenshots

PDF Viewer by Nutrient4 screens
calmdocs3 screens

Verdict

The call

The clearest difference is in-app purchases: calmdocs at none against PDF Viewer by Nutrient's 2. calmdocs also leads on update cadence (every 9 days vs monthly). PDF Viewer by Nutrient's advantage is device support (4 vs 2). On price, ads 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. PDF Viewer by Nutrient sells 2 in-app purchases, starting at $6.99 per 3 months. calmdocs asks for nothing beyond the download.

UpkeepUpdate frequency

PDF Viewer by Nutrient ships an update monthly, calmdocs every 9 days. The most recent releases landed on October 21, 2026 and October 11, 2026 respectively.

Scorecard3 real differences · 7 level
PDF Viewer by Nutrient versus calmdocs: the parameters behind the verdict, then further details
ParameterPDF Viewer by Nutrientcalmdocs
PriceFreeFree
Rating4.6 (9.1K ratings) — better—
Positive reviews73.4% of reviews—
Number of ratings9.1K — better—
Update frequencyMonthlyEvery 9 days — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFreemium—
DevicesiPhone, iPad, Mac, Vision Pro — betteriPhone, iPad
Requires iOS17.0 — better17.6
Further details — not scored
Size112 MB9 MB
Age rating4+4+
DeveloperPSPDFKit GmbHElaine Bevington

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

calmdocs

Not enough reviews yet to summarise bugs or requests.

In-app purchases

2 purchases

PDF Viewer by Nutrient

Subscriptions2
  • PDF Viewer Pro 3 Months7 Days trial$6.993 Months
  • PDF Viewer Pro Yearly7 Days trial$19.991 Year
None

calmdocs

No in-app purchases

Questions

Is PDF Viewer by Nutrient free?
PDF Viewer by Nutrient is free to download, with in-app purchases available.
Is calmdocs free?
calmdocs is free to download, with no in-app purchases.
Do PDF Viewer by Nutrient or calmdocs have ads?
Neither PDF Viewer by Nutrient nor calmdocs shows ads.
Which is updated more often, PDF Viewer by Nutrient or calmdocs?
PDF Viewer by Nutrient ships an update monthly, and calmdocs every 9 days. Most recently, PDF Viewer by Nutrient was updated on October 21, 2026 and calmdocs on October 11, 2026.

Other comparisons