JSONinja - Advanced JSON Viewer

A fast, lightweight viewer for JSON, JSON Lines, JSONC and JSON5, built with Tauri. Installers are about 2-5 MB. Open huge files, search for values within the keys you care about, and fix broken files in place.

Website: jsoninja.dabworx.com

Features

🚀 Core Features

• Multi-tab Interface - Work with multiple JSON files simultaneously
• Large File Support - Handle massive JSON files with 1+ million lines efficiently
• File Operations - Load JSON files, paste content, or use recent files menu
• Real-time Validation - Instant JSON syntax validation and error reporting
• JSON Lines, JSONC and JSON5 - Opens .jsonl/.ndjson (one record per line, each labeled with its line, with unreadable lines flagged individually), JSON with comments (.jsonc, and .json files like tsconfig.json that contain comments), and JSON5. Saving keeps the original format, comments included
• Fix Broken Files - Invalid JSON opens as text with the exact line and column of the problem highlighted. Fix it, watch it re-check as you type, and save it back
• Edit and Save - Edit any document with Edit JSON and save with Ctrl/Cmd + S; the file keeps its original line endings
• Format & Minify - Pretty-print or minify JSON with one click
• Search & Navigation - Powerful search with key/value filtering and highlighting
• Tree View - Collapsible JSON structure with state-preserving expand/collapse controls
• Array Index Display - Shows [0], [1], [2] indices for easy array navigation (toggleable)
• String Length Badges - Character count display for long strings with configurable threshold
• Full-Screen Mode - Distraction-free viewing with F11 toggle
• Recent Files - Quick access to your last 10 opened JSON files
• Character Encoding Detection - Automatic detection and handling of files with special characters (Latin-1/ISO-8859-1)
• Windows Context Menu - Right-click any .json file to open directly in JSONinja
• Automatic Updates - Offers new releases when they come out and installs them in one click (Help > Check for Updates Automatically to turn off)

🎨 Customization

• 4 Built-in Themes - Dark, Light, GitHub, and Monokai with theme-aware rainbow brackets
• Font Customization - Choose from 5 coding fonts (Fira Code, Monaco, Source Code Pro, JetBrains Mono, Cascadia Code) with adjustable sizes
• Color Coding - Individual color controls for keys, strings, numbers, booleans, null values, and brackets
• Rainbow Brackets - 8-color cycling bracket system for visual nesting clarity
• Display Options - Toggle array indices, string length badges, line numbers, word wrap
• Smart Settings - Configurable string length threshold (10-100 characters)
• State Preservation - Tree expansion state maintained when toggling display options

🔍 Advanced Search

• Multi-mode Search - Search keys, values, or both
• Search Within Keys - Limit a value search to certain keys, e.g. find "okafor" only in name and email fields. See Searching Within Keys
• Real-time Highlighting - Instant visual feedback
• Navigation Controls - Previous/next result navigation with keyboard shortcuts
• Match Counter - See total matches and current position

⌨️ Keyboard Shortcuts

• Ctrl/Cmd + T - New tab
• Ctrl/Cmd + W - Close tab
• Ctrl/Cmd + O - Open file
• Ctrl/Cmd + S - Save
• Ctrl/Cmd + F - Find/Search
• Ctrl/Cmd + E - Expand all
• Ctrl/Cmd + Shift + E - Collapse all
• Ctrl/Cmd + , - Settings
• F11 - Toggle full-screen mode
• Esc - Close dialogs/panels

📦 Downloads

Get the latest version from the Releases page:

Platform	File
Windows installer	JSONinja_<version>_x64-setup.exe
Windows portable (no install)	JSONinja-Portable-v<version>-x64.exe
macOS (Intel + Apple Silicon)	JSONinja_<version>_universal.dmg
Linux	.AppImage, .deb or .rpm

Quick Install

Windows:

1. Run the installer, or just run the portable exe
2. Windows 11 already has everything needed. On Windows 10, the installer adds the WebView2 runtime if it's missing; the portable exe needs WebView2 to already be installed (it usually is, via Edge)

macOS:

1. Open the DMG and drag JSONinja to Applications
2. The app isn't notarized yet, so the first time, right-click it and choose Open

Linux:

1. Download the AppImage
2. Make executable: chmod +x JSONinja*.AppImage
3. Run it: ./JSONinja*.AppImage

View All Releases | Report Issues

Building from Source

Prerequisites

• Node.js (v18 or higher)
• Rust (stable)
• The Tauri system prerequisites for your OS (MSVC build tools on Windows, Xcode tools on macOS, WebKitGTK on Linux)
• Git

Step 1: Clone the repository

git clone https://github.com/KrunchMuffin/JSONinja.git
cd JSONinja

Step 2: Install dependencies

npm install

Step 3: Run in development mode

npm run dev

Step 4: Build (optional)

npm run build

Installers end up in src-tauri/target/release/bundle/, and the standalone exe/binary in src-tauri/target/release/.

Build Targets

• Windows: NSIS installer + portable exe (x64)
• macOS: DMG (universal: Intel + Apple Silicon)
• Linux: AppImage + DEB + RPM (x64)

Releases are built by GitHub Actions when a v*.*.* tag is pushed. The workflow creates a draft release with notes from CHANGELOG.md.

Usage Guide

Getting Started

1. Launch the app - Start with the welcome screen
2. Load JSON - Click "Load JSON File" or "Paste JSON"
3. Multi-tab - Use Ctrl+T to open new tabs for multiple files
4. Navigate - Use the tree view to explore JSON structure

Supported Formats

Format	Extensions	How it's shown
JSON	.json	A collapsible tree
JSON Lines	.jsonl, .ndjson	One entry per record, labeled with its line in the file ("line 12": {...}). Lines that can't be read are listed in a banner and shown as text, so one bad line doesn't hide the rest
JSON with comments	.jsonc, and .json files with comments or trailing commas (tsconfig.json, VS Code settings)	The data as a tree. Edit JSON shows the comments, and saving keeps them
JSON5	.json5	The data as a tree. NaN and Infinity are shown in quotes, since plain JSON has no way to write them

A .json file (or pasted text) that isn't plain JSON is tried as JSON Lines, JSON with comments and JSON5 before it's reported as invalid.

Loading JSON Data

• From File: Click "Load JSON File" or use Ctrl+O
• Right-Click: Right-click any JSON, JSON Lines, JSONC or JSON5 file and select "Open with JSONinja"
• Recent Files: Quick access to your last 10 opened files via menu
• Paste: Click "Paste JSON" and paste your content
• Drag & Drop: Drag JSON files directly onto the application

Customizing Appearance

1. Open Settings - Click settings button or press Ctrl+,
2. Choose Theme - Select from Dark, Light, GitHub, or Monokai
3. Adjust Fonts - Pick font family and size
4. Customize Colors - Set colors for each JSON data type
5. Configure Behavior - Toggle features like auto-expand, data types, etc.

Search Functionality

1. Open Search - Press Ctrl+F or click the search icon
2. Choose Mode - Select Keys, Values, or Both. With Values, you can also search within keys
3. Navigate Results - Use arrow buttons or Enter/Shift+Enter
4. Visual Feedback - Matches are highlighted in yellow, current match in orange

Searching Within Keys

Find a value only where it appears under certain keys, anywhere in the file:

1. Press Ctrl+F and select Values. An in keys box appears next to the search box.
2. In in keys, type the key names to search, separated by commas: name, email
3. Type what you're looking for in the search box: okafor

"name": "Maya Okafor",               <- found
"email": "maya.okafor@example.com",  <- found
"notes": "Call Okafor first"         <- skipped: "notes" isn't listed

• Key names match exactly, ignoring case: name finds name and Name, not username
• The search text matches anywhere in the value, ignoring case
• Array items count under the array's key: in keys: tags searches every item in "tags": [...]
• In JSON Lines files it works across every record, e.g. in keys: level with error finds every error in a log
• Leave in keys empty to search all values

Fixing and Editing Files

• Broken files open as text instead of just an error. The bar at the top says what's wrong and where (e.g. expected , or } (line 5, column 3)), that line is highlighted, and Go to error jumps to it. It re-checks as you type, and View formatted shows the tree once it's valid
• Edit JSON in the sidebar edits any document, and Ctrl+S saves it. Saving only writes to files you opened (or picked with Save As), keeps the file's line endings and its read/write permission settings (not its owner or access-control lists, which can be reset by the save), and asks before you close a tab with unsaved changes
• Very large files (over 20,000 lines or 2 MB) are too big to edit in JSONinja; if one is broken, it shows the lines around the problem so you can fix it in a text editor

View Controls

• Expand/Collapse - Click arrows next to objects/arrays (state preserved when toggling settings)
• Expand All - Ctrl+E expands everything
• Collapse All - Ctrl+Shift+E collapses everything
• Array Indices - Toggle [0], [1], [2] display for arrays (default: on)
• String Length - Show character count for long strings with configurable threshold
• Stats Bar - Coming back soon!
• Path Display - Coming back soon!
• Rainbow Brackets - Color-coded bracket nesting with 8-color cycle
• Full Screen - F11 for distraction-free viewing
• Line Numbers - Toggle in quick settings

File Structure

JSONinja/
├── package.json             # Version number and the Tauri CLI
├── src/                     # The viewer (plain HTML/CSS/JS, no build step)
│   ├── index.html
│   ├── styles.css           # All application styles including themes
│   ├── renderer.js          # Application logic & state management
│   └── native-bridge.js     # Connects renderer.js to the Rust backend
├── src-tauri/               # Native side
│   ├── tauri.conf.json      # Window, security policy, bundling, file associations
│   ├── capabilities/        # What the page is allowed to call
│   └── src/
│       ├── main.rs          # Menus, commands, single instance, opening files
│       ├── files.rs         # Encoding detection, settings, recent files
│       └── registry.rs      # Windows "Open with JSONinja" registration
├── CHANGELOG.md
└── README.md

Development

Adding New Themes

1. Edit the CSS custom properties in styles.css
2. Add new theme option in renderer.js
3. Update theme selector in settings panel

Adding New Features

1. UI Components - Add to index.html and style in styles.css
2. Logic - Implement in renderer.js
3. Settings - Add to settings object and persistence
4. Keyboard Shortcuts - Add to handleKeyboardShortcuts method

Customizing Colors

The app uses CSS custom properties for theming:

• --json-key - Object keys
• --json-string - String values
• --json-number - Number values
• --json-boolean - Boolean values
• --json-null - Null values
• --json-bracket - Brackets and punctuation
• --json-object - Object bracket colors
• --json-array - Array bracket colors
• .bracket-level-0 through .bracket-level-7 - Rainbow bracket colors

Troubleshooting

Common Issues

App won't start

• Windows: make sure the Microsoft Edge WebView2 runtime is installed
• Linux: make sure WebKitGTK 4.1 is installed (libwebkit2gtk-4.1-0 on Debian/Ubuntu)
• Building from source: run npm install and check the terminal for Rust errors

.json files still open in another app (Windows)

• Windows only lets you choose a default app yourself: use File > System Integration > Make JSONinja the Default for JSON Files... and pick JSONinja in Settings
• If they still open in the app you used before, it's a known issue on Windows 11 25H2: Settings saves your new choice, but an older saved choice from a previous Windows version can take priority. Go to Settings > Apps > Default apps, click Reset at the bottom, then make JSONinja the default again. Resetting also clears your choices for other file types

JSON won't load

• Verify JSON syntax is valid
• Check file encoding (should be UTF-8)
• Try pasting content instead of file loading

Search not working

• Ensure JSON is loaded and valid
• Check search mode (keys/values/both)
• Clear search and try again

Settings not saving

• Check file permissions in app data directory
• Try resetting to defaults
• Restart the application

Performance

• Handles JSON files up to ~10-20MB (performance depends on structure complexity)
• Use "Collapse All" and disable array indices for better performance with large files
• String length badges can be disabled to reduce visual clutter
• Tree state preservation maintains performance during setting changes
• Search may be slower on very large files

Platform-Specific Notes

Windows

• The installer registers JSONinja for .json, .jsonl, .ndjson, .jsonc and .json5 files and lists it in Settings > Default apps. Windows only lets you choose a default app yourself, so if these files still open in something else, use File > System Integration > Make JSONinja the Default for JSON Files..., which opens JSONinja's page in Settings. The portable exe registers itself the same way when you use that menu item
• Uses the system WebView2 (Chromium-based Edge) engine

macOS

• Uses the system WebKit engine
• Not yet code-signed or notarized

Linux

• Uses WebKitGTK

Contributing

Bug reports, ideas, and pull requests are welcome. See CONTRIBUTING.md for how to build the app and what to include in a pull request. Please report security problems privately, as described in SECURITY.md.

This project follows the Contributor Covenant.

License

MIT License - feel free to use and modify as needed.

Credits

Built with ❤️ using:

• Tauri - Small, secure cross-platform desktop apps
• json5 - JSON5 parsing (MIT License, bundled in src/vendor/)
• Modern CSS - Custom properties and grid
• Vanilla JavaScript - No frameworks needed