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Free online JSON formatter and validator with syntax highlighting and error line numbers. Use as default for beautify+validate+minify in one place; for two-file comparison use json-diff, for schema generation use json-schema-generator. Input: JSON ≤10MB. Returns formatted JSON or line-numbered error. 100% private.
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Formats JSON with syntax highlighting using colored keys, strings, numbers, and booleans, plus line numbers for easy reference. Supports configurable indentation, key sorting, full-text search with navigation arrows to jump between matches, auto-format on paste, and displays input statistics (character count, line count, key count, depth).
Reading raw JSON from APIs or logs is painful without syntax highlighting and line numbers. This tool makes JSON instantly readable with search and navigation, and the auto-format paste feature eliminates the extra step of hitting a Format button.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
API developers reading JSON responses, data analysts exploring JSON datasets, and developers debugging JSON configuration files.
Paste JSON into the input area; auto-format on paste instantly beautifies it with highlighting
Adjust indent size (2 or 4 spaces) and toggle key sorting on or off
Use the search bar to type a key or value; matching lines are highlighted with navigation arrows
View input stats: character count, line count, key count, and maximum nesting depth
Toggle line numbers on/off and copy the formatted output
Invalid JSON shows a parse error with line number and character position for debugging
Input: '{"users":[{"name":"Alice"}]}' pasted with auto-format. Output: Colored, indented JSON showing 'users' as a key (purple), 'Alice' as a string (green), line numbers 1-4.Input: Search for 'email' in a 500-line JSON document. Output: 12 matches highlighted with prev/next navigation arrows.What syntax highlighting colors are used?
Keys are typically blue/purple, strings green, numbers orange, booleans red, brackets gray.
Does auto-format work for partial or invalid JSON?
It attempts to format valid portions and highlights the error location.
Can I copy only a selection of the formatted JSON?
Use the copy all button; for partial copy, select text manually.
What does the depth stat mean?
It shows the maximum nesting level of objects/arrays in the JSON.
Authoritative specifications, standards, and in-depth reading for JSON Formatter.
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Compare two JSON documents and highlight added, removed, and changed keys with line-level diff. Use when comparing API responses or configs; for single-document formatting use json-formatter, for validation errors use json-validator. Input: two JSON texts ≤10MB. Returns highlighted diff. 100% client-side.
Validate JSON syntax and report errors with line numbers without reformatting. Use when only correctness matters; for auto-fix and formatting use json-formatter. Input: JSON text ≤10MB. Returns valid/invalid + error location. 100% client-side.
Compress JSON by stripping whitespace for smallest payload. Use when preparing production payloads; for readable output use json-formatter or json-beautifier. Input: JSON text ≤10MB. Returns minified JSON or line-numbered error. 100% client-side.
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