Free Online JSON to CSV and Excel Converter

Overview

A high-performance, browser-based utility designed for developers, data analysts, and researchers to transform structured JSON data into common spreadsheet formats (CSV and XLSX). The application prioritizes privacy by performing all operations locally in the browser memory, eliminating the risk of data leaks associated with server-side processing.

Core Features

• Instant Conversion: Rapid transformation using optimized streaming libraries (PapaParse for CSV, SheetJS for XLSX).
• Deep Flattening: Automatically handles nested JSON objects, converting hierarchical data into a flat, tabular structure.
• Live Preview: Provides a responsive, sortable data table view after conversion for verification before downloading.
• Input Validation: Real-time syntax checking of JSON input with helpful error messages for missing brackets or invalid characters.
• File Upload/Paste Support: Allows users to upload .json files or paste raw JSON text directly.
• Responsive Design: Fully mobile-optimized layout for desktop and tablet usage.

Technical Specifications

• Architecture: Single-file HTML5/Vanilla JS application.
• Storage Compliance: Strictly no usage of localStorage, sessionStorage, or cookies. The app must maintain application state exclusively within volatile memory (JavaScript objects/variables).
• Sandbox Safety: Does not use alert(), prompt(), or confirm(). All interactions (errors, success messages) are handled via custom modal overlays constructed using HTML/CSS.
• CDN Integration: Must import required dependencies (e.g., papaparse.min.js, xlsx.full.min.js, tailwindcss.min.css) from reliable, standard CDNs.
• Browser Compatibility: Must handle files of reasonable size (up to 50MB) without blocking the main UI thread by using efficient processing or informing the user.

User Interface (UI) & User Experience (UX)

• Layout Structure:
  • Top Navigation: Clean title and brief instruction helper.
  • Input Area: Two-column split (Left: JSON Text Input, Right: Configuration options e.g., 'Flatten nested objects', 'Include headers').
  • Action Area: Prominent primary buttons: "Convert to CSV" and "Convert to Excel".
  • Results Area: A scrollable preview table that appears only after processing.
• Aesthetic Guidelines:
  • Theme: Strict light-mode only. Use a palette of Slate, Indigo, and White.
  • Typography: Sans-serif (system stack) with clear, high-contrast text.
  • Transitions: Smooth fade-ins for the results table and hover-scale effects for action buttons.
  • Shadows: Soft, subtle shadows for input containers to create depth without clutter.

Color Palette

• Primary: Indigo-600 (Actions/Buttons)
• Background: Slate-50 (Neutral background)
• Card/Container: White (Input/Preview containers)
• Text: Slate-900 (Main), Slate-600 (Labels)
• Borders/Dividers: Slate-200