JSONForge
JSON Formatter, Validator & Diff Tool
RFC 8259 JSON formatter, validator, LCS diff comparator, RFC 9535 JSONPath explorer & TypeScript generator. 100% private — runs locally in your browser.
{
"name": "Infinity AI",
"type": "Organization",
"projects": [
{
"name": "Neuromantix",
"modules": 146,
"language": "Rust",
"loc": 96000
},
{
"name": "Vitalis",
"modules": 345,
"language": "Rust",
"loc": 207000,
"builtins": 1723
},
{
"name": "HARNESS Engine",
"model": "30B Sparse MoE",
"language": "Rust + wgpu",
"tokPerSec": 16.37
},
{
"name": "Project SPINE",
"vertebrae": 33,
"language": "Rust",
"scanLatencyUs": 0.2
},
{
"name": "ChronoFact",
"tokenPruningPct": 81.8,
"language": "Rust",
"tests": 124
},
{
"name": "Void LLM",
"params": "303M",
"language": "Rust + CUDA",
"tokPerSec": 7800
}
],
"stats": {
"totalLOC": 360000,
"totalTests": 8500,
"totalAcademies": 13,
"rustVsPython": "139x faster"
},
"url": "https://infinitytechstack.uk",
"active": true
}Why JSONForge?
Format & Beautify
Transform messy, minified JSON into cleanly indented RFC 8259 output. Configurable indentation with 2, 4, or 8 spaces.
Line & Column Validation
Instant syntax validation resolving exact 1-based line and column error coordinates across V8, SpiderMonkey, and WebKit engines.
8 Example Templates
Load production presets for REST APIs, package.json, GeoJSON, Cloud Config, GraphQL, MCP 2025-11-25 manifests, and AI Agent tool schemas.
Tree View & JSONPath
Inspect nested hierarchies visually or query payloads with IETF RFC 9535 JSONPath selectors (wildcards, negative indices, and recursive descent).
LCS JSON Diff Compare
Compare two JSON payloads side-by-side with Longest Common Subsequence (LCS) line alignment to pinpoint additions, removals, and edits.
True UTF-8 Byte Sizing
Measure exact UTF-8 byte counts via TextEncoder (RFC 8259 §8.1) alongside minification savings—accurate for emojis and multi-byte text.
Browser-Local + Web Worker
All parsing, formatting, and 50KB+ background Web Worker execution run strictly in your browser with zero server uploads.
TypeScript & File Export
Generate clean TypeScript interfaces (including multi-dimensional GeoJSON arrays), copy to clipboard, or download as formatted.json.
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
Is JSONForge free to use?
Yes, JSONForge is entirely free, requires no account, and runs entirely in your web browser for maximum privacy.
Is my JSON data sent to a server?
No. All RFC 8259 parsing, validation, UTF-8 byte calculation, diffing, and Web Worker processing happen locally in your browser. Your data is never uploaded to any server, ensuring complete security and privacy.
What does the JSON Diff tool do?
The JSON Diff tool normalizes two JSON payloads and applies Longest Common Subsequence (LCS) line alignment to highlight exact additions, deletions, and modifications side-by-side without cascading line-shift false positives.
Does JSONForge support AI Agent schemas and MCP server manifests?
Yes. JSONForge includes 8 built-in presets including Model Context Protocol (MCP 2025-11-25 protocol and server.json registry manifests), JSON Schema Draft 2020-12 tool schemas, and multi-model AI Agent specs (gpt-6-astra, claude-sonnet-5-5, gemini-4-argon).
Which JSONPath expressions and TypeScript conversions are supported?
The Path tab supports IETF RFC 9535 JSONPath selectors including root ($), dot and bracket notation, negative array indices, wildcards ([*]), and recursive descent (..). The TypeScript tab generates nested interfaces and multi-dimensional array types directly from valid JSON.
How are JSON byte sizes and syntax error positions calculated?
Byte sizes are computed in true UTF-8 octets via TextEncoder per IETF RFC 8259 Section 8.1 rather than UTF-16 string length, accurately measuring emojis and non-ASCII characters. Syntax errors resolve 1-based line and column coordinates across V8, SpiderMonkey, and WebKit engines.