One-click repair for broken JSON, JSON5, JS objects, Python dicts and truncated LLM output.
Select a node to view details
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.
Removes trailing commas after the last element of objects and arrays without touching commas inside string literals.
Converts single-quoted strings to JSON double quotes and escapes embedded quotes correctly, including O'Reilly-style apostrophes.
Quotes bare JS identifiers used as keys and maps Python True/False/None plus undefined, NaN and Infinity to valid JSON values.
Auto-closes strings, objects and arrays that were cut off mid-output — perfect for truncated ChatGPT or Claude responses.
Drop any invalid JSON, JSONC, JSON5, JS object or Python dict into the input. The error panel appears instantly.
Press the green Auto-Fix button (or the one in the error bar) to repair and pretty-print the document in place.
Verify the repaired structure in the Tree or Table view, then copy or download clean standard JSON.
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 |
Trailing commas, single-quoted strings, unquoted keys, // and /* */ comments, Python True/False/None, undefined/NaN/Infinity values, markdown code fences and output truncated mid-way.
No. The repair engine is a pure lexical state machine running entirely in your browser — nothing ever leaves your device.
Yes. Unclosed strings are terminated and every unclosed bracket is auto-closed in reverse order, so cut-off responses parse cleanly.
Yes — line comments (//) and block comments (/* */) are stripped outside of string literals, preserving # and // inside quoted text.
The tool keeps the standard error bar with line and column navigation so you can fix the remaining issue manually, then re-run Auto-Fix.