Comparison

Calca vs Zotero

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

Head to head
About

Calca

This app is an advanced symbolic calculator and text editor. It solves equations, simplifies expressions, and allows you to explain your work alongside calculations. Calculations update instantly as you type, and all data is stored as plain text for easy sharing and device syncing.

Highlights
  • Symbolic calculation
  • Equation solving
  • Expression simplification
  • Markdown text editor
  • Real-time updates
  • Unit and currency conversion
  • Matrix operations
Features
Read full description

Calca is a powerful symbolic calculator that gives you instant answers as you type. It solves equations and simplifies complex expressions - it's a computer algebra system in your pocket! It's also a rich Markdown text editor so that you can explain your ideas alongside your calculations. Calca is perfect for professionals and students - anyone who works with numbers and equations. Variables and functions can be created with only a few keystrokes and can be manipulated with a rich library of operators and functions. Calca updates as you type - just like a spreadsheet. You can declare variables, edit their values and watch everything update before your eyes. Since everything is calculated on the device - no network needed - you get answers instantaneously. All calculations are stored as plain text so you can easily share them with other editors and move them from device to device. Calca has been designed to work with iCloud documents so all your devices can access your calculations - you'll always have the latest files ready for viewing and editing. Calca comes with a suite of examples to help you get started covering topics from home mortgages to kinetics. All these examples are fully explained within Calca itself. Are you still using a desktop calculator? Are you using the calculator with the giant buttons that came with your OS? Computers are much more capable than doing simple one-line arithmetic - put your machine to work with Calca! Calculation Features: • Variables `x = 42` • Functions `f(c) = 9/5*c + 32` and even recursive functions • Units `42 mph in kmph` and currency `¥599 in $` • Solves equations (`x + 2x + 4x = 42`, what is x?) • Matrices with inverses so you can solve linear equations • Sum, prod, map, and reduce operations on lists, matrices, and ranges • Trigonometry and complex numbers • Derivatives of functions • Logic operations and if statements • Binary math (& and |) and support for binary and hex number (`0xA9` and `0b1010`) • Keeps track of units (m, s, m/s, m/s^2, etc.) so you can verify your equations as you compute Please visit http://calca.io to see lots of examples. Thank you for looking!

About

Zotero

This research tool helps you collect, organize, annotate, cite, and share your academic and professional work. Save articles, books, and webpages, add notes and highlights, and generate bibliographies in thousands of styles. Collaborate with others and sync your library across devices.

Highlights
  • Collect research from various sources
  • Organize with collections and tags
  • Annotate PDFs and webpages
  • Generate citations and bibliographies
  • Collaborate in group libraries
  • Sync across devices
Features
Read full description

Zotero is a free, easy-to-use research tool that helps you collect, organize, annotate, cite, and share your work. COLLECT • Save journal articles, newspaper articles, books, webpages, and more via the Share button in Safari and other apps • Automatically download article PDFs to read • Quickly add physical books and articles to your Zotero library by scanning book barcodes or article DOIs with your iPhone or iPad camera ORGANIZE • Use collections and tags to organize your research • View and edit bibliographic information for your research items ANNOTATE • Read PDFs, EPUBs, and webpage snapshots and add highlights and notes, or use an Apple Pencil to make freehand annotations CITE • Instantly generate citations and bibliographies in over 10,000 formats and journal styles including APA, Chicago, IEEE, MLA, Turabian, and Vancouver SHARE • Collaboratively collect sources and mark up PDFs in group libraries with your colleagues • Synchronize your personal and group research libraries to access them via Zotero’s desktop app and the Zotero website • Use the Zotero desktop app to insert your annotations into Word, LibreOffice, and Google Docs documents and automatically generate bibliographies from the sources you used Visit zotero.org to learn more about everything you can do with Zotero. Having trouble? Have an idea? Post bug reports and feature requests to the Zotero Forums at forums.zotero.org to talk directly to Zotero developers. ZOTERO AND PRIVACY Since 2006, the Zotero team has been committed to creating the best research software, and we believe that includes putting you in full control of your own work. We’re an independent, nonprofit organization, and we’ll never sell your data.

Screenshots

Calca4 screens
Zotero2 screens

Verdict

The call

The clearest difference is price: Zotero at Free against Calca's $9.99. Zotero also leads on in-app purchases (none vs 2) and update cadence (every 2 weeks vs every 5 months). On rating, review sentiment, ratings volume and ads 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

Zotero is free to download; Calca costs $9.99 up front. Calca sells 2 one-off in-app purchases. Zotero asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 4.5 for Calca against 4.6 for Zotero. Both are backed by a comparable volume of ratings — 153 and 425 respectively. Written reviews are what separate them: 76% of Calca's written reviews are positive against 78% of Zotero's.

UpkeepUpdate frequency

Calca ships an update every 5 months, Zotero every 2 weeks. The most recent releases landed on September 25, 2026 and September 24, 2026 respectively.

Scorecard4 real differences · 6 level
Calca versus Zotero: the parameters behind the verdict, then further details
ParameterCalcaZotero
Price$9.99Free — better
Rating4.5 (153 ratings)4.6 (425 ratings) — better
Positive reviews76.5% of reviews77.9% of reviews — better
Number of ratings153425 — better
Update frequencyEvery 5 monthsEvery 2 weeks — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS15.0 — better16.6
Further details — not scored
Size78 MB197 MB
Age rating4+4+
DeveloperKrueger Systems, Inc.Zotero

Customer experience

Calca

All ratings153 ratings
Positive87.6%
Neutral4.6%
Negative7.8%
Written reviews170 reviews
Positive76.5%
Neutral7.1%
Negative16.5%

Zotero

All ratings425 ratings
Positive89.6%
Neutral4.7%
Negative5.6%
Written reviews262 reviews
Positive77.9%
Neutral10.3%
Negative11.8%

User reviews

Calca

From 153 App Store ratings

What we love

  • 💡 Unique blend of text editor and calculator
  • 📝 Markdown support for documentation
  • 🔄 Dynamic recalculation of all values
  • ⚙️ Powerful mathematical and algebraic capabilities
  • 📊 Unit conversion and unit-aware calculations

Room to improve

  • 🐛 Magic Keyboard input bugs on iPad
  • ⚠️ Appears abandoned or poorly maintained
  • 🐛 Text selection issues with external keyboards
  • 📱 iPad landscape mode problems
  • 🐛 Cursor jumping and screen jumping during editing

Zotero

From 425 App Store ratings

What we love

  • 👍 Simple and powerful
  • 🚀 Convenient and useful
  • 🚀 Seamless syncing across devices
  • 🚀 Excellent reference management
  • 👍 Great annotation and PDF reading experience

Room to improve

  • 🐛 Crashes frequently
  • 🐛 Syncing issues with WebDAV
  • 🐛 Metadata not automatically extracted from PDFs
  • 🐛 Annotation tools could be improved
  • 🐛 Limited sorting and filtering options

Bugs and requests

Calca

Reported bugs

12 issues
  • Magic Keyboard causes number input to overwrite instead of append
  • Text selection before numbers triggers increment/decrement instead of selecting
  • Cursor jumps forward and backward with external keyboards
  • iPad Pro keyboard truncation in portrait mode
  • Arrow key (=>) doesn't work in landscape mode
Show 7 more
  • App crashes on startup on some devices
  • File saving is temperamental and causes data loss
  • Folders don't persist unless calculations created within them
  • Large number calculations lose precision (10^100 + 1 - 10^100 returns 0 instead of 1)
  • Keyboard focus issues on iPad with Magic Keyboard
  • iOS 13+ button adaptation issues
  • Spinning beach ball on very large calculations

Requested features

15 requests
  • Files app and document browser integration
  • Dropbox and Google Drive support
  • Date calculation functionality
  • Looping and iteration support
  • User-defined function storage in separate files
Show 10 more
  • Temperature unit support (Celsius, Fahrenheit)
  • Logarithmic and non-proportional unit definitions
  • Multiple parametric plots simultaneously
  • Landscape mode optimization
  • Tabular data and multi-row markdown table support
  • Dark mode (now implemented)
  • Subscription model option for ongoing development
  • Decimal place formatting control
  • Charting and financial functions
  • Better document management interface

Zotero

Reported bugs

4 issues
  • Unable to unzip PDF snapshots
  • Annotations disappearing or moving unexpectedly
  • Dark mode not working as expected
  • Inability to add citations directly from the app

Requested features

6 requests
  • Eraser tool for annotations
  • More color options for pen and highlighter
  • Ability to open PDFs in external apps
  • Bookmarking and table of contents support
  • Improved search functionality
Show 1 more
  • Offline access to downloaded PDFs

In-app purchases

2 purchases

Calca

One-time2
  • 6-Month Optional Patronage$4.99
  • 12-Month Optional Patronage$7.99
None

Zotero

No in-app purchases

Questions

Is Calca free?
Calca costs $9.99, and also offers in-app purchases.
Is Zotero free?
Zotero is free to download, with no in-app purchases.
Which has better reviews, Calca or Zotero?
Zotero is rated higher. Calca averages 4.5 out of 5 from 153 ratings, while Zotero averages 4.6 from 425 ratings.
Do Calca or Zotero have ads?
Neither Calca nor Zotero shows ads.
Which is updated more often, Calca or Zotero?
Calca ships an update every 5 months, and Zotero every 2 weeks. Most recently, Calca was updated on September 25, 2026 and Zotero on September 24, 2026.

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