Spot the differences in text and image files, or even folders full of files. Review changes in seconds, with the world's most advanced and beautiful file comparison app.

Kaleidoscope 3 marks the comeback of a longtime favorite: completely redesigned interface fitting in perfectly with the latest versions of macOS, dark mode support, native for Apple Silicon. All while staying the best tool for spotting changes in text, images and folders.


- Redesigned interface, including new dark mode and new app icon; Kaleidoscope's design now fits macOS Big Sur and Monterey
- Runs natively on all Macs, including those based on Apple silicon (Apple M1 series).
- Reader view makes it easier to focus on the content
- Greater control over text layout, with better font options and display choices
- Ability to ignore particular folders and files during folder compare, using powerful patterns.
- Persistent top toolbar with convenient Add and Paste buttons
- Redesigned Unified text comparison and File Shelf views to make it easier to review differences and keep track of files being compared
- Powerful filters for comparing items in changeset windows


Two-Way Text Comparison & Merging
- Supports any text file, Word documents, PDF, RTF
- Super-fast diffing of lines and character-level changes
- Directly paste from clipboard
- Three powerful display modes: Blocks, Fluid and Unified
- Color coding to spot added, deleted, and changed text
- Powerful text layout customization
- Reader view that helps focus on content
- Built-in search

Three-Way Merge
- Review code changes and resolve conflicts
- Edit text inline
- Intelligently auto-merge the right content

Powerful Image Comparison
- Supports any file that can be imported as bitmap
- Directly paste from clipboard
- Compare images in four different modes: Two-Up, One-Up, Split and Difference
- Spot subtle pixel differences with a high contrast “difference mask”
- Navigate large images using pan & zoom tools

Folder Comparison
- Ultra-fast algorithm for finding differences in large folders
- Sort and filter down to what is most important
- Powerful ignore patterns to exclude extraneous files and folders
- Drill deeper into folders for more detailed comparisons
- Copy your preferred files across sources

Code Review
- Well-designed overview of all files changed in a changeset
- Find a file by filtering by name or by kind of change
- Inspect changes in text and image files using all of Kaleidoscope's compare tools

Easy Workflow Integration
- Git, Mercurial, Subversion, Bazaar, and Perforce support
- Works as a fully functional diff or merge tool
- ksdiff tool unleashes the power of the unix command-line
- Supported by a growing list of GUI source control management apps
- Integrate with the Xcode debugger (lldb) for text and graphics
- Integrates with tools like Alfred for even faster workflows


"Kaleidoscope epitomizes the concept of “versatile software”: anyone can pick it up and use it, and the app will “scale” according to a user’s needs." - Federico Viticci,

"Kaleidoscope 2 is breeze. I wish I'd had something like Kaleidoscope when I wrote my first novel, and I'll be counting on it when I finally get around to writing the next one." - Rene Ritchie,

"It’s beautifully designed, fast and wonderful to use. It’s become an essential part of my toolkit already." - Matthew Panzarino, The Next Web

"I've been a full-time developer for over a decade, tried other tools, and there's just nothing else that comes close to Kaleidoscope." - Collin Donnell

"The new Kaleidoscope is great, and has awesome and committed people behind it. Devs and designers need this tool." - @SteveStreza


If you have any questions or feedback about Kaleidoscope, please contact us at
Learn about important Kaleidoscope updates and announcements by following @kaleidoscopeapp on Twitter.

What’s New

Version 3.1.2

• The "Open in New Window" option in the open dialog is now off by default, restoring previous behavior
• Items opened as part of a folder comparison no longer get added to the Recent Documents menu
• Fix a sporadic crash when closing documents while scrolling
• Fix a regression in the Integration window
• Fix a text color issue in dark mode

Ratings and Reviews

3.9 out of 5
20 Ratings

20 Ratings

MatthewOden ,

Best Diffing app I've ever used

Kaliedscope has been my diffing tool of choice for the past seven years. It feels expensive for it's value - but at the same time, I haven't been footing the bill.

nextstep0.8 ,

primary window begs for review; ownership change

nice comparisons, expensive upgrade, new owner, remains to be seen if updated more frequently or if any new features, such as the ability to compare .docx files (difficullt, I know; see, e.g., Workshare DeltaView (likely the best of all options, but no longer available, as Workshare purchased Litera, but had moved away from DeltaView to Workshare Compare, which is now in any event based on the Litera Change–Pro codebase. which may have been newer but lacked some obscure features that were possible with DeltaView)), but producing comparisons for .ps (PostScript Level I, II or 3), .pdf and especially the latest supported version of Microsoft's Rich Text Format (.rtf) used by Edit/TextEdit under NeXTSTEP should be doable. Hopefully the portion of the "Compare" window begging for a review will be removed after I've submitted this, as I did pay for the software, and so I'd rather not see advertisements or requests for reviews during my use of the software.

Mikey Ward ,

Still the best

The app has changed hands several times over the years, and continues to be my standout favorite diff tool. Kudos to the new devs for modernizing Kaleidoscope and making it even better~

App Privacy

The developer, Letter Opener GmbH, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Usage Data
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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