JSONForge
JSON Formatter, Validator & Diff Tool
Format, validate, compare, and explore JSON data. Tree view, diff mode, syntax highlighting. Free, private — runs entirely in your browser.
{
"name": "Infinity AI",
"type": "Organization",
"projects": [
{
"name": "Neuromantix",
"modules": 108,
"language": "Rust",
"loc": 84000
},
{
"name": "Vitalis",
"modules": 345,
"language": "Rust",
"loc": 196000
},
{
"name": "Void LLM",
"params": "303M",
"language": "Rust + CUDA",
"tokPerSec": 7800
}
],
"stats": {
"totalLOC": 347000,
"totalTests": 8206,
"rustVsPython": "139x faster"
},
"url": "https://infinitytechstack.uk",
"active": true
}Why JSONForge?
Format & Beautify
Transform messy, minified JSON into beautifully indented, readable code. Configurable indentation with 2, 4, or 8 spaces.
Instant Validation
Get real-time validation with precise error messages showing exactly where the syntax error is. No guessing, no frustration.
6 Example Templates
Load realistic example data for REST APIs, package.json, GeoJSON, CloudConfig, GraphQL, and more. Learn JSON structure by example.
Tree View Explorer
Navigate complex JSON structures with our visual tree view. See keys, types, and values at every nesting level at a glance.
JSON Diff Compare
Paste two JSON objects side-by-side and instantly see the differences highlighted. Perfect for API debugging and config comparisons.
Size Comparison
See formatted vs minified byte counts and compression savings. Know exactly how much whitespace your JSON contains.
100% Private
Zero server requests. All processing happens in your browser using native JSON.parse/stringify. Your data never leaves your machine.
Export & Share
Copy formatted JSON to clipboard or download as a .json file. Ready to use in your codebase, API, or configuration.
Common Use Cases
API Development
Format and inspect REST API responses. Debug payloads, validate response shapes, and compare API versions side-by-side with diff mode.
Package Management
View and edit package.json, tsconfig.json, and other config files. Validate syntax before committing to version control.
GeoJSON & Mapping
Format and validate GeoJSON for mapping applications. Inspect coordinates, feature properties, and geometry types.
Cloud Configuration
Validate cloud infra configs (Terraform, AWS, Docker Compose). Catch syntax errors before deploying to production.
GraphQL Debugging
Inspect GraphQL responses, format query results, and compare mutations. Tree view makes deeply nested data easy to navigate.
Testing & QA
Compare expected vs actual JSON outputs. Diff mode highlights exactly what changed between test runs or API versions.
Frequently Asked Questions
What's the maximum JSON size I can format?
JSONForge runs entirely in your browser, so the limit depends on your device's memory. In practice, it handles files up to 5-10MB without issues. For very large files (50MB+), consider using command-line tools like jq.
Does JSONForge support JSON5 or JSONC (comments)?
Currently JSONForge uses the browser's native JSON.parse, which follows the strict JSON specification. JSON5 features like comments, trailing commas, and unquoted keys are not supported. Strip comments before pasting.
How does the diff comparison work?
The diff tool formats both JSON inputs with 2-space indentation, then compares them line-by-line. Lines that differ are highlighted — red for the left side (removed) and green for the right side (added). It's a visual diff, not a semantic one.
Is my data sent to any server?
No. JSONForge processes everything client-side using your browser's built-in JSON.parse() and JSON.stringify(). Zero network requests are made. Your data stays on your machine.
Can I use JSONForge offline?
Once the page loads, all functionality works without an internet connection. The tool has no server dependencies — it's pure JavaScript running in your browser.