Format, validate, and prettify JSON data with syntax highlighting. Perfect for developers working with APIs and data structures.
Working with REST APIs? Paste messy JSON responses, validate structure, and format with proper indentation. Quickly identify errors in API payloads, debug request/response data, and document API examples for team collaboration.
Catch syntax errors before deploying! Paste your JSON data and instantly see validation errors with line numbers and detailed messages. Find missing commas, brackets, or quotes that break your JSON files.
Optimize JSON for production! Remove whitespace and reduce file size by 30-60%. Perfect for API responses, configuration files, and data transmission where bandwidth matters. Improves website load times.
Explore nested JSON structures visually! Switch to tree view to expand/collapse objects and arrays. Perfect for understanding complex API responses, configuration files, or analyzing deeply nested data structures.
Make JSON readable! Convert minified or single-line JSON into properly indented, pretty-printed format. Essential for code reviews, debugging, and understanding JSON structure at a glance.
Create clean JSON examples for documentation! Format sample API requests/responses, configuration examples, or data schemas. Copy formatted JSON directly into README files, wikis, or API documentation.
Missing Comma: {"name": "John" "age": 30}
Fix: Add comma between properties: {"name": "John", "age": 30}
Trailing Comma: {"name": "John",}
Fix: Remove last comma: {"name": "John"}
Single Quotes: {'name': 'John'}
Fix: Use double quotes: {"name": "John"}
Unquoted Keys: {name: "John"}
Fix: Quote property names: {"name": "John"}
Formatting (pretty-printing) adds indentation and line breaks so structure becomes visible: one glance shows which objects nest where, and which bracket closes what. APIs deliberately send JSON minified — whitespace is wasted bandwidth — so nearly every debugging session starts by pretty-printing a response. Validation checks the text against the JSON grammar and pinpoints the exact character where parsing fails, turning "invalid JSON somewhere in 2,000 lines" into "line 847, unexpected comma". Minifying is the reverse of formatting: strip every non-essential byte before shipping a config or payload.
{"a": 1,} — legal in JavaScript, fatal in JSON. The most common error by far, usually introduced when deleting the last item of a list.{'name': 'x'} fails, {"name": "x"} parses.{name: "x"} is a JavaScript object literal, not JSON.// comments (VS Code settings, for instance) are JSONC — a different, looser format.undefined, NaN, and Infinity don't exist in JSON; only null does. Python's True/None must become true/null.“ ”) that look right and parse wrong.A validator earns its keep because JSON errors cascade confusingly: one missing quote at line 12 can produce a parser complaint about line 200. Fix the first reported error and re-validate — later errors are usually echoes of it.
JSON (JavaScript Object Notation) became the lingua franca of APIs because it maps directly onto the data structures every language already has: objects/dictionaries, arrays, strings, numbers, booleans, and null — six types, nothing else. Dates, for instance, don't exist in JSON; they travel as ISO-8601 strings or Unix timestamps by convention (our Timestamp Converter translates the latter). When your JSON needs to become a spreadsheet, the JSON to CSV converter flattens it; when comparing two API responses, format both here first and then use the Text Diff tool so the comparison aligns line by line. New to the format entirely? Start with our JSON for beginners guide.
No — parsing, formatting, and validation run entirely in your browser, so API responses containing real customer data are safe to paste.
Multi-megabyte payloads format fine; browsers only struggle beyond tens of megabytes. For giant log dumps, format just the object you're inspecting.
Only to humans: whitespace is ignored by parsers. Two spaces is the common convention in the JavaScript ecosystem; pick what your team reads best.
Then the JSON is syntactically fine and the API dislikes the content — a missing required field, wrong type, or schema violation. Check the API's error body and documentation; syntax was the part this tool ruled out.
No — only whitespace changes. Values, key order, and structure are preserved exactly; minifying then formatting returns byte-identical data.