Format and validate
Paste or type JSON and use Format to pretty-print it with consistent indentation and alphabetically sorted object keys—the same canonical layout the app uses everywhere. When your document matches that layout, a small indicator shows that the JSON is valid and aligned with the app’s formatted output. Parse problems appear in a dedicated error area so you can fix them without losing context.
Line-numbered editor
The main editor shows line numbers and scrolls independently from the tree. When you jump to a search hit, the matching line is highlighted so you can line up structure with raw text quickly.
Tree explorer
A collapsible tree mirrors your document: keys, array indices, and values with color hints for strings, numbers, and other types. Expand and collapse nodes to focus on a subtree. Control-click (or right-click) a row to Copy JSON for just that value or subtree, or Load Node to open it as a new history entry for deeper work.
Search
Search is debounced so large payloads stay responsive while you type. Results list both structural matches and plain-text hits, with line numbers where available. Choosing a result expands the tree path to that node and scrolls the editor to the right line. Use ⌘F to focus the search field.
History, pins, and groups
Successful formats can be saved to a History sidebar so you can revisit recent JSON without hunting for files. You can pin important entries, rename them for clarity, or organize them into custom groups you create and rename. Scroll positions in the text editor and tree, plus which nodes were expanded, are remembered per entry when you switch between them.
In Settings (JSON Max menu), you can choose how many recent history entries to keep (within a sensible range).
Clipboard and files
- Paste JSON appears when the clipboard looks like JSON, so you can pull payloads in with one click.
- Copy sends the current editor contents to the clipboard; the button briefly confirms success.
- Save writes the current JSON to a file you choose (standard save sheet).
- Open
.jsonfiles from Finder or drag them onto the app; the main window loads them like a paste operation, without spawning extra empty windows.
Designed for long sessions
The interface uses a calm, layered layout tuned for macOS: clear hierarchy, readable monospace in the tree, and a minimum window size that keeps the editor, tree, and optional search results usable together.