Input
Actions
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Format
Output
About This Tool
I built this JSON formatter after countless hours debugging API responses and config files with malformed JSON. Whether you're a backend developer testing REST APIs, a frontend engineer working with configuration files, or a DevOps specialist managing deployment manifests, clean JSON formatting is essential. This tool instantly validates your JSON syntax, highlights errors with line numbers, and beautifies minified data into readable, properly indented format. Unlike desktop editors that require installation, this runs entirely in your browser with zero data leaving your machine—perfect for handling sensitive production configs or customer data.
How to Use
Paste or type your JSON into the input panel. The tool automatically validates syntax in real-time, showing errors with precise line and column numbers. For beautifying: click Format to convert minified JSON into readable indented format (2 or 4 spaces). For minifying: use Compact to remove whitespace and reduce file size for production. The tool handles nested objects, arrays, Unicode characters, and escaped strings correctly. Works great with API responses from curl commands, clipboard data from browser DevTools, or exported database records. Supports both JSON and JSONC (JSON with Comments) formats for configuration files. The syntax validator catches common mistakes like missing commas, unclosed brackets, trailing commas, and invalid escape sequences.
Common Use Cases
API Response Debugging
Copy a minified API response from Network tab, paste here to see the structure clearly and identify missing fields.
Config File Validation
Before deploying nginx or kubernetes configs in JSON format, validate syntax to catch typos like trailing commas or unquoted keys.
Data Transformation
Clean up exported data from databases or spreadsheets before importing into another system.
Database Query Results
Format JSON responses from MongoDB queries or PostgreSQL JSON columns to understand document structure.
REST API Testing
When testing APIs with tools like Postman or curl, format the JSON responses to verify the data structure matches your expectations.
Configuration Management
Format JSON configuration files for applications like VS Code settings, package.json, or webpack.config.js to review and edit settings.
Log Analysis
Parse JSON-formatted log entries from services like CloudWatch, ELK stack, or application logs to extract meaningful information.
Data Migration
When migrating data between systems, format JSON exports to validate data integrity and structure before importing.
Frontend Development
Format JSON fixtures and mock data used in unit tests or development environments to ensure test data matches production schemas.
API Documentation
Format example request/response payloads in API documentation to make them readable for developers integrating with your API.
Error Debugging
When APIs return error responses in JSON format, format them to clearly see error codes, messages, and debugging information.
Authentication Tokens
Format JWT payloads (JSON Web Tokens) to inspect user claims, permissions, and token expiration details.
Limitations & Important Notes
This tool validates against standard JSON specification (RFC 8259). It does NOT support: JSON5 extensions (trailing commas, comments, unquoted keys), JSONC (JSON with Comments used by VS Code), or non-standard formats. For very large files (>10MB), performance may degrade—consider using command-line tools like jq for batch processing. The formatter preserves string content exactly as-is, so pre-escaped Unicode or HTML entities remain escaped.
Created by Sofyan Setiawan – Full-Stack Developer
Software engineer with 8+ years of experience building web applications, developer tools, and API integrations. Creator of CodingTool.dev, helping developers with everyday coding tasks.