Jace
A native JSON editor for Mac
Explore JSON as a tree, edit the source beside it, and compare two documents to see exactly what changed—with search, formatting, parse feedback, and Quick Look.
Version 1.1 · Requires macOS 15 or later
JSON without losing sight of its structure
Compare, semantically
- Compare the open document with a file, your clipboard, or pasted text
- Differences are matched by key and value, so you see real changes rather than shifted lines
- Counts and filters for added, removed, and changed, with a navigator for the whole hierarchy
- Inspect both sides of a difference together, with the JSON path ready to copy
- Decide whether object property order counts; arrays are always compared by position
Explore and edit
- Expand and collapse objects and arrays
- Edit keys, strings, and numbers directly in the tree, and toggle booleans with a click
- Duplicate, sort, or remove any node, and drag nodes to reorder them or move them elsewhere
- Select several nodes with ⇧-click or ⌘-click and remove them together, as one undo step
- Select a tree node to jump to its source, or place the cursor in the source to highlight the matching node
Find and format
- Search across keys and values, with matches highlighted and a count you can step through
- Prettify or minify from the toolbar or with keyboard shortcuts
- Choose your indentation width and editor font size
- See line numbers, syntax highlighting, document size, line count, and JSON parse status
Built for real-world files
- Familiar macOS document workflows for opening, editing, saving, and undoing changes
- A launch screen to start a draft, paste the clipboard, open a file, or compare two inputs
- A dedicated large-file mode for documents 50 MB and up, loading source sections on demand
- Recent files and in-progress drafts always within reach
- A Quick Look extension for previewing .json files right in Finder
See it in action
Support
Getting started
- Open Jace and start a new draft, paste from the clipboard, or open a .json file from the launch screen or Finder.
- Use the tree on the left to explore objects and arrays.
- Use the source editor on the right for direct text editing.
- Select a tree item to jump to its source. Placing the cursor in the source highlights the matching tree item.
- Right-click a tree item to duplicate, sort, or remove it, or drag it to a new position.
- Choose Compare (⇧⌘D) to compare the document with a file, your clipboard, or pasted text.
Keyboard shortcuts
| Prettify | ⇧⌘F |
| Minify | ⇧⌘M |
| Find | ⌘F |
| Compare | ⇧⌘D |
| Previous difference | ⌥⌘[ |
| Next difference | ⌥⌘] |
| Close comparison | Esc |
| Toggle Recent Files | ⇧⌘R |
Common questions
Does Jace upload my JSON files?
No. Document parsing, editing, comparison, search, and formatting happen locally. Jace uses Firebase Crashlytics for crash reports and Firebase Analytics for anonymous feature-usage counts, but never sends file names, paths, or JSON contents. See the Privacy Policy for details.
How is comparing different from a text diff?
Jace parses both documents and matches them by key and value, so reformatting or reordered object properties don’t show up as changes. You can choose whether object property order counts; arrays are compared by position.
Why does the tree show a parse error?
The source is not currently valid JSON. The status bar shows the affected line and parser message. Correct the syntax and the tree will update after parsing completes.
Does Jace validate JSON Schema?
No. Jace validates JSON syntax and reports parse errors, but it does not currently validate documents against a JSON Schema.
Why can’t I reorder nodes in a very large file?
Duplicating, sorting, and dragging nodes are available for normally parsed documents. Files that open in large-file mode (50 MB and up) support editing values and the source, but not restructuring the tree.
Get in touch
jace@andylia.ngFor help, bug reports, feedback, or feature requests. When reporting an issue, include your Jace version, macOS version, the steps that led to the problem, and any error message. Do not send confidential JSON files—if a sample is needed, remove secrets and personal information first.
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