How do I format and validate JSON online?

Paste your raw JSON into the editor or upload a JSON file. JSON-VIEWER immediately validates syntax and displays formatted, color-coded output with 2-space indentation. You can switch to Tree View or Graph View for structured hierarchy inspection.

Is JSON-VIEWER safe and private for sensitive API data?

Yes, 100% of the parsing, formatting, and conversion happens entirely in your local web browser sandbox. No JSON data, keys, values, or payload information is ever sent to any remote server.

Can this tool repair broken or malformed JSON?

Yes! JSON-VIEWER includes an automated JSON repair engine that fixes trailing commas, unquoted keys, single quotes, escaped characters, and missing brackets automatically with a single click.

How can I convert JSON to TypeScript, YAML, CSV, or XML?

Click on the 'Tools' menu in the top toolbar to instantly convert your JSON into strongly-typed TypeScript interfaces, YAML documents, flat CSV tables, or formatted XML structures.

Does JSON-VIEWER support large JSON files and BigInt numbers?

Yes, JSON-VIEWER features a custom lossless BigInt parser that prevents 64-bit integer truncation (such as Twitter snowflake IDs or database primary keys), and utilizes virtualized rendering to handle large JSON trees smoothly.

JSON-VIEWER - Best Online JSON Formatter, Tree Visualizer & Validator

JSON-VIEWER is a free, high-performance developer tool to view, format, validate, query, repair, and convert JSON data online. Built with strict 100% client-side privacy, no JSON payload ever leaves your web browser.

Key Features

Interactive JSON Tree View: Expand, collapse, search, and copy exact JSONPath and dot-notation paths.
2D Node Graph Visualizer: Visually navigate complex JSON objects and nested hierarchies.
1-Click JSON Error Repair: Automatically fix unquoted keys, trailing commas, single quotes, and syntax errors.
Multi-Format Converter: Convert JSON to TypeScript interfaces, YAML, CSV, and XML instantly.
Lossless BigInt Precision: Preserves 64-bit integer IDs without floating-point truncation.
Monaco Code Editor: Professional syntax highlighting, bracket matching, and code folding.

Frequently Asked Questions

How do I format JSON?

Paste your JSON into the editor and click Format to beautify with standard 2-space indentation.

Is JSON-VIEWER safe and private?

Yes. JSON-VIEWER processes everything locally inside your browser using Web APIs. Zero telemetry or server storage is used.

Can I generate TypeScript interfaces from JSON?

Yes, click Tools > Generate TS Interfaces to create clean, reusable TypeScript types directly from your JSON.