OfflineJsonKit

A fully offline, single-file HTML toolbox that bundles common developer utilities: JSON parsing, Base64 encode/decode (text & image), URL encode/decode, QR code generation, and image compression. No deployment, no server required — just open in browser and go.

Preview

Features

📝 JSON Parser

• Format and prettify JSON
• Minify JSON
• Syntax-highlighted output
• Collapsible nodes
• Clear input and copy results with one click
• Dark theme UI

🔄 Encoding Conversion

• Base64 text encode/decode
• URL encode/decode
• Image ↔ Base64 conversion
  • Upload local images and convert them to Base64
  • Paste Base64 and preview images
  • Copy Base64 results with one click

📱 QR Code Generator

• Generate QR codes offline from any text or link
• Works fully offline with no network requests
• Download QR codes as PNG images
• Adds a white quiet zone to improve scan reliability

🗜️ Image Compression

• Compress images fully offline, similar to TinyPNG / Squoosh, with no server upload
• Target-size mode: set a target size (KB/MB) and it auto-searches quality and scales down if needed
• Quality-slider mode: manually adjust the compression quality and see the resulting size in real time
• Output as JPEG / WebP, with an optional max width/height limit
• Shows original size, compressed size and reduction ratio, with one-click download

🌐 Bilingual UI

• Automatically selects Chinese or English based on browser language
• Chinese browsers default to Chinese; other browser languages default to English
• Manual language switching is persisted with localStorage

💾 Local Storage

• Uses browser localStorage to save the language preference
• Input auto-save is currently disabled, so refreshing the page does not restore previous input

📦 Project Structure

json_parsing/
├── index.html              # Core application file (single HTML, ~90KB)
├── vercel.json             # Vercel deployment config
├── README.md               # Chinese documentation
├── README.en.md            # English documentation
├── VERSION.md              # Version history (v1.0 ~ v1.26)
├── LICENSE                 # License
├── README.assets/          # Chinese README screenshots
│   └── screenshot-zh.png
└── README.en.assets/       # English README screenshots
    └── screenshot-en.png

🚀 Quick Start

Option 1: Local Use (Recommended)

Open index.html directly in your browser. No installation required.

# Clone the project
git clone https://github.com/user/json_parsing.git
cd json_parsing

# Open in browser
open index.html        # macOS
start index.html       # Windows
xdg-open index.html    # Linux

Option 2: Deploy to Vercel

The project includes vercel.json for easy deployment to Vercel static hosting.

# Install Vercel CLI
npm i -g vercel

# Deploy
vercel

🛠️ Tech Stack

Layer	Technology
Frontend	Single HTML file, embedded CSS + JavaScript
QR Code	Embedded qrcodejs library (with Reed-Solomon error correction)
Image Compression	Canvas native encoding
i18n	Custom lightweight implementation, navigator.language + localStorage
Storage	Browser localStorage
Deployment	Vercel static site

Changelog

See VERSION.md for detailed version history.

Current version: v1.26 (2026-06-19)

Highlights

• ✨ Single file, zero dependencies, fully offline
• 🎨 Clean and compact dark theme UI
• 🔒 Privacy-friendly: data is not uploaded to any server
• 🚀 Fast response and local processing
• 🌐 Chinese/English bilingual support
• 📱 QR codes generated completely offline

License

MIT License