How it works
How to use the JSON Parser
Paste JSON
Or open a file.
Inspect the tree
Expand objects and arrays, search, and copy the path to any value.
Fix errors
Invalid JSON shows the line, column and a suggested fix.
Built for developers
Why developers use it
Private by design
Everything runs locally in your browser. No uploads, no tracking of your data, no accounts.
Precise errors
Exact line and column, a plain-English explanation and a suggested fix for every syntax error.
Lossless formatting
Big integers, decimals and escapes are preserved byte-for-byte. Only whitespace changes.
Built for large files
A background worker, virtualised rendering and a fast custom parser keep big files smooth.
Tree explorer
Collapsible, searchable tree with JSONPath copying and jump-to-source.
Works offline
Install it as an app or keep using it without a connection once loaded.
FAQ
Frequently asked questions
How strict is the parser?
Fully RFC 8259 compliant: no comments, trailing commas, single quotes or unquoted keys — but each problem gets a precise, friendly message.
Is my JSON sent to a server?
No. Parsing, validation, formatting and the tree view all run in your browser using JavaScript and a Web Worker. Your data never leaves your device. You can even use the tool offline once the page has loaded.
How large a JSON file can I open?
Files of tens of megabytes work well on a modern laptop. Processing runs in a background thread so the page stays responsive, the editor only renders what is visible, and the tree view is virtualised. The hard limit is 200 MB per file.
Does formatting change my numbers?
Never. Many online formatters use JSON.parse, which silently rounds big integers (like 64-bit IDs) and rewrites numbers such as 1.0 or 1e3. This tool keeps every number and string escape exactly as you wrote it — only whitespace changes.
Keep going
Related tools
- JSON FormatterFormat, validate and explore JSON
- JSON ValidatorFind and fix JSON syntax errors
- JSON ViewerExplore JSON as a searchable tree
- JSON CompareFind semantic differences between two JSON documents
- JSON DiffSide-by-side or unified line diff of two JSON files
- JSON EditorEdit JSON with live validation
- JSON to CSVConvert JSON arrays to CSV and CSV back to JSON
- JSON to XMLConvert JSON to XML and XML to JSON