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Turn any JSON payload into clean TypeScript interfaces or type aliases — merge arrays, detect optional fields and unions.
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Format, validate, and explore JSON — 100% client-side, private by design
Paste XML, get clean JSON — attributes, repeated elements and text nodes handled correctly
Turn CSV rows into JSON arrays of objects — quoted fields, custom delimiters and types handled for you
Flatten nested JSON into clean CSV columns — download Excel-ready .csv files in one click
Compress JSON to a single line and watch exactly how many bytes you save
Compare two JSON documents semantically — key order and whitespace never count as differences
Escape JSON strings for embedding — or unescape stringified logs back into readable JSON
One-click repair for broken JSON, JSON5, JS objects, Python dicts and truncated LLM output.
Turn any JSON payload into clean TypeScript interfaces or type aliases — merge arrays, detect optional fields and unions.
Parse YAML configs — K8s, Docker Compose, GitHub Actions — into clean JSON, then explore and edit visually.
Generate clean, idiomatic YAML from any JSON — smart string quoting, compact list style, 2 or 4 space indent.
Serialize JSON to well-formed XML — @_ attributes, repeated elements, text nodes and safe tag names.
Infer a standards-compliant JSON Schema from example data — formats, required keys, unions and additionalProperties control.
Query any JSON with live JSONPath evaluation — wildcards, recursive descent, slices and filters, all in your browser.
Elements of heterogeneous arrays merge into one interface; fields missing from some elements become optional with ?
Fields holding mixed string/number/null values collapse into precise union types like string | null.
Switch between interface and type alias output with one checkbox — root name is fully customizable.
Tweak the JSON in the Tree or Table view and the generated TypeScript updates instantly.
Insert an API response or any JSON document into the input panel.
The TypeScript interface appears in the dedicated TS tab — adjust the root name or switch to a type alias.
Copy the definitions to your clipboard or download them as a ready-to-use types.d.ts file.
How formatjson.net compares to traditional server-based JSON formatters and converters
| Capability / Standard | formatjson.net (Client-Side Workbench) | Traditional Server-Based Tools |
|---|---|---|
| Data Processing & Privacy | 100% local in-browser JavaScript — payloads never leave your device | Often uploads JSON/XML/CSV to remote backend servers |
| Confidential API Keys, JWTs & PII | Safe by design — zero network transmission, works offline via Service Worker | Risk of server access logs or third-party data retention |
| Broken & Truncated LLM JSON Repair | 1-click lexical state machine fixes comments, single quotes, trailing commas, Python literals & unclosed brackets | Fails with syntax error on non-strict JSON |
| 64-Bit Snowflake IDs & Leading Zeros | Preserves unsafe integers (> 2^53 - 1) and leading-zero codes ("00123") without precision loss | Silently truncates 64-bit IDs or strips leading zeros |
| Deep Nested Array Exploration | Interactive spreadsheet drill-down ([n items] →) with breadcrumbs, 3-state sorting & inline cell editing | Flat root-only tables or read-only trees |
| Large File Responsiveness | Chunked lazy tree (200 nodes/batch) + paginated table + 150 KB highlight guard | Main-thread DOM freeze on multi-megabyte files |
When an array contains objects where a key is missing in some elements, that key is emitted with a ? marker.
Yes. Nested objects are rendered as inline object type literals, and arrays of objects merge into a single element type.
interface supports declaration merging; type aliases are more flexible for unions. The tool outputs either with one click.
A field observed as both string and null becomes a union type string | null, never silently dropped.
No. Type inference runs entirely in your browser — perfect for private API payloads.