OnEdit User Guide

Welcome to OnEdit, a native macOS text editor focused on speed, clarity, and practical workflows. This guide reflects the 3.0 feature set.

What's New in 3.0

Smart Actions: Rewrite, shorten, adjust tone, summarize, or explain selected text with Apple Intelligence/Foundation Models support when available.
Smart Actions use Apple Intelligence/Foundation Models on device when available, and OnEdit leaves documents unchanged if support is unavailable.
Review before replacing: Generated text opens in a review sheet before it replaces the original editor selection.
Movable toolbar: Choose View > Toolbar Edge to place editor tools on the right, left, top, or bottom edge.
Clearer document state: Unsaved tabs show an asterisk, and Window > Set Window Size... adds direct width and height controls.

Choose File > New Window (⌘N) for a separate workspace.
Close a tab with ⌘W; close all tabs with ⌥⌘W.
Control-click a tab for Close Other Tabs and Close Tabs to the Right.
When another OnEdit window is already active, opening a file prefers that active window when possible.
The main window restores tabs and the workspace on launch.
Tabs with unsaved changes show an asterisk after the tab name until saved.
Choose Window > Set Window Size... to enter exact width and height values for the active editor window.

OnEdit edits plain text; rich text is normalized on paste.
Syntax highlighting is applied automatically by file extension.
Toggle the toolbar with View > Hide Toolbar (⌃⌘T).
Move the editor toolbar with View > Toolbar Edge, then choose Right, Left, Top, or Bottom.
Toggle line numbers with View > Show Line Numbers (⇧⌘L) or the editor context menu.
Press Option (⌥) or ⌥⌘C to toggle Column Selection Mode; press again to exit.
Drag to select a column block; typing edits multiple lines at once.
Paste Most Recent Copy: ⌥⌘V.
Show Copy History: ⌃⌥⌘V or Edit > Show Copy History....
Paste from Copy History is available in the Edit menu and editor context menu.
Format Document (⌘L) supports JSON and C-style languages.
Print text and supported previews with ⌘P.

Open a Markdown file in Preview, then click Trust workspace to execute.
Runnable fence languages: sh, bash, zsh, python, python3, node, javascript, js.
Add optional metadata (title, timeout, module mode) in the code-fence info string.
Run one block or click Run all commands to execute blocks in document order.
Each runnable block captures output and a structured execution receipt.
For saved Markdown files, results persist across edit/preview switches and app relaunch until cleared.

Use Edit/Preview for Markdown, HTML, and CSV files; ⇧⌘P toggles preview from the keyboard.
Markdown Preview renders Mermaid fences locally as diagrams instead of raw code blocks.
Rendered Mermaid diagrams include Copy Image and Save PNG… actions in the preview card.
Word and Excel files render in-app; PowerPoint uses macOS Quick Look.
Media files (images, videos, audio) open in a dedicated preview tab, and WebP/SVG are supported.
Drag files into the editor to insert their file path; supported media files show a preview when available.

Base64 Encode / Decode: Works on selected text.
Sort Lines: Sort selected lines alphabetically (ascending/descending).
Remove Duplicate Lines: Clean up lists instantly.
Change Case: Convert selection to Upper Case, Lower Case, or Title Case.
Smart Actions: Select text, then run rewrite, concise, friendly, professional, summarize, or explain actions from Tools > Smart Actions, the toolbar sparkles button, the editor context menu, or the in-place sparkles button.

Switch themes in View > Theme (Light, Dark, System).
Toggle "Vibrancy" (glass effect) in the View menu.
Editor background textures (Paper, Wood, Iron) are available in View > Texture.

Supported languages include: Swift, Python, JavaScript, TypeScript, HTML, CSS, JSON, Markdown, YAML, XML, SQL, C, C++, Ruby, PHP, Java, Go, Rust, and Shell Script.
SQL files are associated with OnEdit and open with SQL highlighting automatically.
The editor auto-detects language based on file extension.
Manually change language via View > Syntax.

A file opens in preview and can't be edited: Some formats are preview-only. Convert to a text format to edit.
File access prompts: Files outside your workspace require permission the first time you open them. Choose File > Open or drag the file into the window.
Format Document doesn't change anything: Formatting currently targets JSON and C-style languages.
Smart Actions are unavailable: Turn on Apple Intelligence in System Settings if your Mac supports it, or select a smaller passage when the selection is too long.