JSON Formatter & Validator Online
Instantly beautify, validate, and minify JSON with color syntax highlighting — plus a built-in TypeScript interface generator and repair mode. Free for developers, API testers, and data engineers. If you work with CSV data or need to validate XML documents, those formatters are just a click away.
How to Use the JSON Formatter
- Paste your raw or minified JSON into the input area on the left.
- Click Format to validate and beautify with 4-space indentation and color highlighting.
- Use Minify to produce a compact single-line output for API payloads or config files.
- Click Repair JSON to auto-fix trailing commas, single quotes, and JavaScript comments.
- Switch to the TypeScript tab to generate typed interface declarations from your JSON structure.
- Click Download .json or Copy Result to export the output.
Key Features
- Color syntax highlighting for keys, strings, numbers, booleans, and null values
- Instant JSON validation with exact error messages on invalid input
- JSON minification — removes all whitespace for compact payloads
- Repair mode — fixes trailing commas, single quotes, JS comments, and unquoted keys
- TypeScript interface generator — derives typed interfaces from any JSON structure, useful alongside a regular expression tester when validating field patterns
- Key count and max depth statistics for understanding JSON complexity
- Download as .json file or copy result to clipboard
- 100% browser-based — no server, no signup, works offline
JSON Formatter Use Cases
Debugging REST API responses
Paste raw JSON from curl, Postman, or browser developer tools to instantly see a readable, color-coded structure. The depth and key count stats help identify unexpectedly large payloads before they reach production.
Generating TypeScript interfaces from JSON
Drop in any API response and switch to the TypeScript tab to get ready-to-use interface declarations. This eliminates manual type writing for large or deeply nested API responses, saving significant development time.
Fixing broken JSON from config files
Many developers write JSON with JavaScript-style comments or trailing commas that standard parsers reject. Repair JSON mode silently cleans these issues, making the JSON valid without manual find-and-replace work.
Minifying JSON for production builds
Strip all whitespace from large JSON datasets or configuration files before bundling. The Minify button reduces file size immediately, and the byte counter confirms the savings.
FAQ's
It parses your JSON, validates its syntax, and renders the output with proper indentation and color-coded syntax highlighting. It can also minify, repair, generate TypeScript interfaces, and show key count and depth statistics — all in the browser.
Paste your JSON and click Format. Valid JSON renders immediately with color highlighting. Invalid JSON shows a red error message with the exact location and description of the syntax problem.
After formatting valid JSON, switch to the TypeScript tab. The generator recursively analyzes the JSON structure and produces named TypeScript interface declarations for every nested object, handling arrays, unions, and primitives.
Repair mode removes single-line and block JavaScript comments, strips trailing commas before closing brackets and braces, converts single-quoted strings to double quotes, and adds double quotes around unquoted object keys.
No. Every operation runs entirely in your browser using JavaScript. Your JSON data never leaves your device and is never stored, logged, or transmitted to any external server.
Key count shows the total number of keys across all nested objects in the structure. Depth reports the maximum nesting level — a flat object has depth 1, a singly-nested object has depth 2, and so on.
Yes. Click Minify to remove all whitespace and produce a compact single-line string. The byte counter updates to show the size reduction. Click Download .json to save the minified file.
Yes. Once the page is loaded, all formatting, validation, minification, repair, and TypeScript generation run entirely client-side with no further network requests required.
Related Tools
Toolaroid's free online JSON formatter is designed for developers who need instant, reliable JSON validation without uploading data to a third-party server. Whether you are debugging a REST API response, preparing a configuration file, or converting a JSON payload into typed TypeScript interfaces, every operation runs entirely in your browser. The color syntax highlighting makes large, deeply nested structures easy to scan, while the key count and depth stats surface complexity at a glance. Bookmark this page for your daily JSON workflow — no account, no rate limit, no ads.
Guides & Use Cases
Step-by-step guides for specific workflows