Yes. Completely free, no sign-up, no paywall, no premium tier. Every feature is available to everyone, forever - including formatting, diff, conversion, and analysis.

Does JSON Studio store or transmit my data?

No. All processing runs entirely in your browser via JavaScript. Your JSON, logs, or API responses never leave your device - zero server calls for any tool input. Safe for sensitive payloads including production secrets, customer PII, and internal API responses.

How do I format JSON online?

Paste JSON into the Format tool and click Format. JSON Studio beautifies with proper indentation instantly, even for deeply nested structures. Live syntax highlighting shows keys (cyan), strings (green), numbers (orange), booleans (purple), and nulls (red) in distinct colors.

Can JSON Studio fix broken JSON?

Yes. Auto-Fix repairs trailing commas, single quotes, and unquoted keys - the three most common JSON syntax mistakes. Always review auto-fixed output before using it in production, since heuristic repairs can occasionally produce unintended results on edge cases.

How do I compare two JSON objects?

Use JSON Diff. Paste both objects in panels A and B, then click Compare. Added keys are marked with +, removed with −, and changed values with ~. The summary shows total changes by category - added, removed, changed, unchanged.

What does the API Cleaner do?

It removes all null and undefined values from API responses recursively, can flatten deeply nested objects into dot-notation keys (e.g. user.address.city), and strips empty strings, arrays, and objects. Perfect for prepping responses before display, storage, or further processing.

How does the Request Converter work?

Provide a JSON request specification with url, method, headers, and body fields. The tool generates equivalent code in cURL (for terminal), JavaScript Fetch (browser-native), or Axios (npm library) - preserving all headers, methods, and request bodies.

What's the difference between minify and format?

Format adds whitespace and indentation to make JSON human-readable. Minify removes all unnecessary whitespace to reduce file size - typically 30-50% smaller. Use Format for development and debugging; use Minify for production responses where bandwidth matters.

JSON Studio – Free JSON Formatter, Validator & Converter

01 / Format

Format & Minify JSON

Beautify, minify, validate, and auto-fix broken JSON with intelligent error detection and live syntax highlighting.

Input

JSON INPUT

Output

FORMATTED OUTPUT

// Formatted output will appear here

02 / Cleaner

API Response Cleaner

Remove null values, flatten nested objects, and sanitize messy API responses instantly.

API Response

RAW RESPONSE

Cleaned Output

CLEANED

// Cleaned output will appear here

03 / Diff

JSON Diff

Compare two JSON objects and instantly see what was added, removed, or changed - with key-by-key precision.

JSON A - Original

ORIGINAL

JSON B - Modified

MODIFIED

04 / Logs

Log Analyzer

Paste server or application logs to instantly count errors, warnings, info messages, and group error types.

Log Input

PASTE LOGS

05 / Convert

Request Converter

Convert API requests between cURL, JavaScript Fetch, and Axios with full header and body support.

Input Format

{"url": "https://api.example.com/users", "method": "POST", "headers": {"Content-Type": "application/json"}, "body": {"name": "John"}}

Request JSON

INPUT

Generated Code

OUTPUT CODE

When to use JSON Studio

Five everyday developer workflows where this toolkit replaces a console session, a script, or a paid SaaS.

Debugging

Inspect API responses fast

Paste a minified production response, click Format, and immediately see the structure with color-coded keys, strings, numbers, booleans, and nulls. No need to pipe through jq or a Node REPL.

// Before - unreadable {"user":{"id":1042,"name":"Jane","email":null,"roles":["admin"]}} // After Format { "user": { "id": 1042, "name": "Jane", "email": null, "roles": ["admin"] } }

Data Cleaning

Strip nulls before storage

Many APIs return verbose payloads with null fields for unset properties. The API Cleaner recursively removes them, often shrinking responses by 30-60% before you persist or transmit.

For deeply nested objects you only need to query, the Flatten action collapses everything to dot-notation keys (user.address.city) - perfect for CSV exports, analytics dashboards, or flat key-value stores.

remove-nulls flatten deep-clean

Code Review

Spot config drift

Compare two versions of a config file, schema definition, or API contract with JSON Diff. Added keys appear in green, removed keys in red, changed values in amber - all annotated with the exact path so you know what shipped vs what's staged.

Especially useful for environment configs: paste prod and staging side-by-side to catch unintended differences before they cause an incident.

config-drift schema-changes env-compare

Workflow

Postman-to-cURL in one click

Need to share an API call with a teammate, drop into a runbook, or paste into a bug report? The Request Converter takes a JSON request spec (url, method, headers, body) and emits equivalent code in three formats:

cURL - for terminal sharing
Fetch - for browser console & React
Axios - for Node.js services

Inside the toolkit

No black boxes. Every transformation is built on standard JS and a tiny custom tokenizer - fully transparent, fully client-side.

Format & Minify

Native JSON.parse + JSON.stringify

Format calls JSON.parse(input) to validate and parse, then JSON.stringify(parsed, null, 2) to pretty-print with 2-space indentation. Minify uses the same parse step but stringifies without the indent argument - yielding the most compact valid JSON.

Validation is automatic: any parse error is caught and shown inline with the exact character position from the V8 / SpiderMonkey error.

Auto-Fix

Three regex repairs

The fixer applies three patterns that cover ~90% of malformed JSON:

Trailing commas: ,(\s*[}\]]) → strip
Single quotes: ' → "
Unquoted keys: {key: → {"key":

The result is then run through JSON.parse to confirm validity. Always review fixes before using in production.

Syntax Highlighting

Custom tokenizer, zero deps

The highlighter walks the input character-by-character, classifying each token: strings (with key vs value detection by lookahead for :), numbers, true/false/null, brackets, and punctuation. It works on partial or invalid input - no dependency on a parser, so the editor never breaks while you type.

Color tokens: keys in cyan, strings in green, numbers in orange, booleans in purple, nulls in red.

JSON Diff

Top-level key comparison

Diff parses both inputs with JSON.parse, computes the union of keys, and classifies each key as added (only in B), removed (only in A), changed (different value), or unchanged. Values are compared via JSON.stringify for deep equality.

Output is rendered with line-level color stripes and a summary chip for each category.

Format. Validate. Transform.

Format & Minify JSON

API Response Cleaner

JSON Diff

Log Analyzer

Request Converter

Common questions

When to use JSON Studio

Inspect API responses fast

Strip nulls before storage

Spot config drift

Postman-to-cURL in one click

Inside the toolkit

Native JSON.parse + JSON.stringify

Three regex repairs

Custom tokenizer, zero deps

Top-level key comparison

Format. Validate. Transform.

Format & Minify JSON

API Response Cleaner

JSON Diff

Log Analyzer

Request Converter

Common questions

When to use JSON Studio

Inspect API responses fast

Strip nulls before storage

Spot config drift

Postman-to-cURL in one click

Inside the toolkit

Native JSON.parse + JSON.stringify

Three regex repairs

Custom tokenizer, zero deps

Top-level key comparison

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