Compatibility Changes - Introduce CotEditor Syntax, a new syntax definition format. The legacy YAML-based syntax definition format is now deprecated, and user-created syntaxes are automatically migrated on first launch. New Features - Adopt smarter syntax parsing powered by tree-sitter for multiple built-in syntaxes, improving syntax highlighting and outline extraction in C, C#, C++, CSS, Go, HTML, Java, JavaScript, Kotlin, LaTeX, Lua, Makefile, Markdown (outline extraction only), PHP, Python, Ruby, Rust, Scala, Shell Script, SQL, Swift, and TypeScript. - Display symbolic icons next to outline items. - Allow collapsing outline items in the Outline inspector for tree-sitter-based and structured document syntaxes. - Add the “Wrap Lines” option to the Outline inspector. - Make smart indentation aware of the current syntax. - Expand comment delimiter settings in syntax definitions, allowing multiple delimiters and related options. - Add detailed delimiter settings for strings, characters, and indentation to syntax definitions. - Add the Multiline option to highlighting rules in syntax definitions so matches can span multiple lines. - Show the current position in search results in the Find field while navigating between matches, for example, “2/5”. - Add CurrentLine and ReplaceCurrentLine to the UNIX script input/output keywords for editing the current line in the editor. - Add Bulgarian localization. Improvements - Update the inspector’s appearance on macOS Tahoe 26. - Improve the syntax-highlighting algorithm for legacy regex-based parsing. - Update built-in syntaxes. - Use the user’s window size setting for the Zoom action, if available. - Improve word selection and related editing actions to treat commas as word delimiters. - Improve general text-editing performance. - Hide line numbers in the window titlebar area when the navigation bar is hidden on macOS Tahoe 26. Fixes - Fix incorrect syntax parsing in some built-in syntaxes. - Fix an issue where the default file extension in the Save dialog was .txt for syntaxes with a file extension not registered in the system. - Fix an issue where TSV multiple replace definitions could fail to overwrite an existing definition when re-imported. - Fix an issue where TSV multiple replace definitions could not import empty replacement strings. - Fix an issue where key bindings imported from a settings archive could be lost after relaunching the app. - Fix issues in the file browser where items could point to the wrong location after being moved or renamed. - Fix an issue in the file browser where replacing a file with a folder, or vice versa, could leave the displayed state outdated. - Fix an issue in the file browser where newly created or duplicated items could fail to become selected immediately in some folders. - Fix issues where the Script menu could become outdated after changes in the Scripts folder. - Fix an issue where line reordering commands could insert extra blank lines in documents using CRLF line endings. - Fix an issue where AppleScript could return an unclear error when a folder document had no current document. - Fix an issue where requesting a zero-length text range via AppleScript could return an unintended character. - Fix an issue where some decimal setting values could use the wrong number format and be reset unexpectedly in certain locale configurations.

Improvements - Improve stability on MacBook Pro models with Touch Bar. Fixes - Fix a crash on exporting settings when some setting values are not customized. - Fix a potential crash in Find All when a matched line is extremely long. - Address a potential crash when editing a keyboard shortcut in the snippets settings.

Improvements - Create a new document from a UNIX script only when output is available, using the %%%{CotEditorXOutput=NewDocument}%%% option. - Improve overall stability. Fixes - Fix an issue where the default file extension for Markdown documents was .txt instead of .md. - Fix an issue where snippets were not included in the settings export. - Fix an issue where settings imported from a settings archive incorrectly included filename extensions. - Fix an issue where invisible characters were not printed even if the “Print Invisible” option in the print settings was enabled. - Fix descriptions in the user guide for UNIX scripting. - Address a potential crash in the file browser when creating, duplicating, or moving files. - Address a potential crash when a document was modified by another process.

Fixes - Fix an issue where smart indentation did not work under certain conditions. - Fix an issue in the Find window where syntax highlighting for regular expressions could break for some patterns. - Fix an issue where the editor incorrectly highlighted paired symbols when an escaped symbol was nearby. - Fix an issue in the file browser where TypeScript documents were incorrectly displayed with a video icon. - Address a potential crash when pasting multiline text into the editor under certain conditions. - Address a potential crash when closing a document.

New Features - Add AppleScript support for `folder document`, including the `current document` property and forwarding of `document` commands. Improvements - Optimize the performance of scanning incompatible characters. - Accept the JSON5 format when importing custom themes and multiple replace definitions. - Improve the behavior of trailing whitespace trimming. - Update the JSON syntax to highlight comments in the JSON5 format. - Improve overall stability. Fixes - Fix an issue where the app could crash when opening a large file while the Warnings inspector was open. - Address an issue where the Save dialog for documents ignored the current syntax for the default file extension.

New Features - Add the `--goto` option to the `cot` command-line tool as syntactic sugar for the `--line` and `--column` options. See `--help` or the user guide for details. - Add Chinese (Hong Kong) localization. Improvements - Improve the text encoding detection algorithm. - Update the C++ syntax to include the .cu and .cuh filename extensions. Fixes - Fix an issue in the syntax editor where the outline title field occasionally became uneditable. - Fix an issue in the Outline inspector where matches filtered by the filter field were not highlighted. - Update the Swift syntax to fix outline extraction.

Improvements - Improve word deletion to treat periods and colons as word delimiters. - Update the filter after duplicating a file in the file browser. - Update the user guide. Fixes - Fix an issue in the file browser where files weren’t hidden when the document’s folder name matched the filter string. - Fix an issue where the app crashed when cutting rectangular selections at the end of a document with CRLF line endings.

New Features - Add a feature to export and import settings to transfer them to another Mac. - Allow opening alias and symlink documents from the file browser. - Request file access permission from the user by the “Open in New Window” command instead of simply presenting an error when CotEditor doesn’t have permission. - Display the original path for alias and symlink files in file preview views. - Support for importing multiple replace definitions from tab-separated values. Improvements - Syntax highlighting now takes nesting into account when highlighting symbol pairs. - Update the Lua syntax to support nested string delimiters. - Update the contents and layout of the user guide. Fixes - Fix an issue in CotEditor 6.1.2 where the text entered in a split editor didn’t match the theme's text color. - Fix an issue where the default syntax setting reverted to Plain Text after a short time when set to None. - Fix an issue where scroll bars in the editor became invisible under certain theme and appearance combinations. - Fix an issue in the Donation settings pane where the purchase button for the one-time donation didn’t work on subsequent attempts. - Address an issue where scrolling the editor with arrow keys caused unexpected jumps.

Improvements - Keep the selection in the file browser when filtering by filename. Fixes - Fix an issue where changing the theme color while a document is in front of the Settings window immediately overwrites the editor’s text color with the selected color. - Fix an issue where an incremental search with the global search text is automatically performed when the application becomes active. - Fix an issue where the file browser prompts an error message when selecting a symlink or alias whose original is unavailable.

Improvements - Reset filename filtering by performing the Add File/Folder commands. Fixes - Fix an issue where the editor doesn’t receive focus by document opening when the system keyboard navigation feature is enabled. - Fix an issue where a focus ring appears in an empty area in the navigation bar by document opening when the system keyboard navigation feature is enabled. - Fix an issue in the file browser where the the items are not sorted when a top-level item was renamed. - Fix an issue in the Quick Action bar where the last input remains. - Fix an issue in editors where the word selection doesn’t expand properly when dragging the mouse.

New Features - Introduce the filter feature in the file browser. - Introduce the “Insert comment delimiters after indent” option to the Edit settings pane. - Revert the “Append a space to comment delimiter” option to the Edit settings pane. - Add Russian localization. Improvements - Improve the algorithm to comment out block comments. - Ignore .git folders in the file browser. - Prevent moving focus to the editor when selecting a document in the file browser. - Update the Verilog syntax to support SystemVerilog. - Update the Swift syntax. Fixes - Fix an issue where the counts in the status bar are occasionally unavailable when the document is opened. - Fix an issue where the text fields in sheet dialogs don’t get focus when they appear.

Improvements - Improve the user interface details on macOS 26. - Enable the enhanced runtime security protections. - Ensure that the sidebar is always displayed when opening a folder document. - Improve the “Open with External Editor” button in file preview views to allow specifying the application to open. Fixes - Workaround an issue on macOS 26 where the editor’s scroller tracks have a different style compared to standard scrollers. - Fix an issue where the counts in the status bar are occasionally unavailable when the document is opened. - Fix an issue in the vertical text orientation where the line number view is tucked beneath the titlebar when the navigation bar is hidden. - Fix an issue in the multiple replacement window where the text selection is unexpectedly canceled. - Fix an issue where the editor in a document opened by replacing with a blank document doesn’t initially have focus. - Fix an issue in the Find All command where the result view doesn’t display the correct document title when the target document was created by replacing with a blank document. - Fix an issue where the line endings pop-up button doesn’t work when the document was opened in a blank document. - Fix an issue in the multiple replacement window where the sidebar can be collapsed. - Fix an issue where the syntax mapping conflict view cannot be closed.

Improvements - Change the default editor font size to 13 pt. Fixes - Fix an issue on macOS 15 where the horizontal scroller appears in editors even when setting lines to wrap. - Address a potential crash on macOS 26 that can occur when opening a document. What’s New in Version 6.0.2 Fixes - Fix an issue on macOS 26 where the application crashes by opening the Donation settings pane while a system theme color other than Multicolor is selected in the System Settings > Appearance. - Fix an issue where the theme setting changes unexpectedly when opening the Appearance settings pane after switching the system appearance mode. - Fix an issue where the indentation style detection doesn’t work.

Fixes - Fix an issue on macOS 26 where the application crashes by opening the Donation settings pane while a system theme color other than Multicolor is selected in the System Settings > Appearance. - Fix an issue where the theme setting changes unexpectedly when opening the Appearance settings pane after switching the system appearance mode. - Fix an issue where the indentation style detection doesn’t work.

Improvements - Avoid assigning the Shift+Return shortcut key for a snippet. Fixes - Fix an issue where the file browser doesn't show the entire filenames when the scroller slot is shown. - Fix an issue where the “Convert Indentation” commands don’t convert if no characters are selected. - Fix an issue where the input fields in the Find window accept rich text. - Fix an issue where folder documents can open multiple windows for the same folder. - Address a potential crash on macOS 26 that occurs when performing a keyboard shortcut. - Address a potential crash on macOS 26 that can occur when opening a document on an Intel-based Mac.

New Features - Support macOS Tahoe 26. Improvements - Change the system requirement to macOS Sequoia 15 and later. - Update the user interface on macOS 26 to the Liquid Glass style. - Update the application icon to the Liquid Glass style. - The options to highlight matching braces have been removed and they are now always highlighted. - Apply the text find highlighting to all split editors. - Move selected items to the Trash by the Delete action in the file browser. - Show also the file size of the previewed document in the status bar. - Display the numbers of registered items below the lists in the syntax editor. - Deprecate the feature to change the editor opacity per window. - Deprecate the feature of installing a custom theme by simply opening the file in CotEditor. - Deprecate the “Make Snake Case,” “Make Camel Case,” “Make Pascal Case,” “Hiragana to Katakana,” and “Katakana to Hiragana” commands in the Text > Transformations menu. - Deprecate the “Draw separator” option for the line number view on macOS 26. Fixes - Fix an issue where the “Convert Indentation” commands don’t convert indentation to the indent style that’s not the default. - Fix an issue where the Syntax toolbar menu is disabled when the toolbar is shown afterward. - Fix an issue where the size of the Multiple Replace window is not stored. - Fix an issue in the Dutch localization where the number of found items isn’t displayed in the Find window.

Improvements - Update the CSS and Go syntaxes to highlight more keywords.

Fixes - Fix an issue in CotEditor 5.2.1 where the text color in the text fields within the Find window appears black in the dark mode.

Improvements - Update the CSS syntax to highlight more keywords. - Update the JavaScript syntax to highlight placeholders in template literals. Fixes - Fix an issue where the state of the Text Replacement option in modes is not saved. - Fix an issue where shortcuts could be assigned in the Key Bindings settings to menu commands that perform multiple replacements, even though these shortcuts didn’t actually work. - Fix an issue where the font in the input fields of the Find window would occasionally be replaced by a fallback font. - Fix an issue where the options button in the advanced character count doesn’t work.

New Features - Allow adding and removing text encodings from the text encoding list, and enabling the handling of a wider range of encodings. - Add the Xcode Project syntax (.pbxproj). - Add the Metal syntax Improvements - Improve differentiation without color. - Update the CSS syntax to highlight more keywords. - Update the HTML syntax to highlight more keywords. Fixes - Fix an issue where opening a document with mixed line endings incorrectly unifies them to the dominant line ending when it is not LF. - Fix an issue where a document containing incompatible characters cannot be closed without lossy saving. - Fix an issue where the text encoding of restored documents could be incorrectly set to Unicode (UTF-8). - Fix an issue where the Option-Delete Forward shortcut deletes the previous word instead of the next word by the multi-cursor editing mode. - Fix an issue in the file browser where the order of renamed items remains unchanged. - Fix an issue where the cached settings remain unchanged after executing the “Reload All Theme,” “Reload All Syntax,” or “Reload All Definitions” commands.

Improvements - Update the HTML syntax to highlight ARIA attributes.

New Features - Enhance the content of the file preview view for the file browser. - Add the “Copy File Path” command to the File menu as an alternative to the “Show in Finder” command, which can be shown while pressing the Option key. Improvements - Update the CSS syntax to add new keywords (thanks to Karam!). - Improve the VoiceOver support in folder documents. - Improve the Spanish localization.

Fixes - Fix an issue where an existing document may unintentionally shift when a new document is opened.

Improvements - Keep syntax highlights by text selection in the Dark mode as well. Fixes - Fix an issue on CotEditor 5.1.4 where the insertion point rarely jumps to the nearest outline item when the outline inspector is shown.

Improvements - Enable the “text replacement” option by default in custom modes. Fixes - Fix an issue on CotEditor 5.1.3 where the app rarely becomes unresponsive when a save is performed. - Fix an issue where the document position doesn’t cascade from the previous document when opening a document while the app is inactive.