What is a JSON formatter?
A JSON formatter takes compact or messy JSON and reprints it with indentation and line breaks so structure is visible. Web6’s formatter also validates, minifies, diffs, and explores JSON without leaving your browser.
Free tools
Free JSON Formatter and Validator
Format, validate, beautify, minify, compare, search, and inspect JSON in a private browser-based editor with syntax errors, tree view, and file download. No account required.
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JSON formatting guide
Practical notes for formatting, validating, and inspecting JSON safely in the browser.
How to format JSON
Paste or upload JSON, choose indentation (2 spaces, 4 spaces, or tab), then choose Format. Valid documents are pretty-printed. Invalid documents show line and column errors instead of silently changing values.
How to validate JSON
Validation checks ECMA-404 / RFC 8259 syntax. You get a pass/fail result plus diagnostics for common mistakes such as trailing commas, single quotes, comments, and unterminated strings.
JSON beautifier vs JSON minifier
Beautifying adds whitespace for humans. Minifying removes unnecessary whitespace for smaller plain-text payloads. Neither replaces transport compression like gzip or Brotli.
What makes JSON invalid?
Typical causes include trailing commas, single quotes, unquoted keys, comments, NaN/Infinity/undefined, functions, control characters in strings, and mismatched brackets.
Common JSON syntax errors
Missing commas between properties, trailing commas before closing braces, unquoted keys, mismatched brackets, and broken escape sequences are the most frequent issues developers hit.
How to read JSON error messages
Start with the reported line and column, inspect the snippet, then apply the explanation. Use Safe Repair only for clear formatting issues and always review the result.
JSON objects vs arrays
Objects are unordered sets of name/value pairs (key order may still matter to some systems). Arrays are ordered lists. Sorting keys never reorders array items in this tool.
JSON vs JavaScript object
JavaScript object literals can use identifiers as keys, single quotes, comments, trailing commas, and functions. JSON cannot. Treat API payloads as JSON, not as JS source.
How to escape JSON
Escaping prepares text for embedding inside a JSON string or code literal. It is not HTML sanitization and does not make untrusted content safe to inject into pages.
How to sort JSON keys
Use Sort keys when you need stable alphabetical ordering for diffs or readability. Meaning is usually unchanged, but UI layers that rely on key order may display differently.
How to compare two JSON documents
Paste original and modified JSON into Compare mode for a structural diff with paths. Prefer structural compare over raw text when whitespace or key order differs.
What is a JSON tree viewer?
A tree viewer expands nested values so you can inspect types, lengths, and paths without drowning in a giant string. Copy paths to use in tests or debugging.
How to handle large JSON files
Stay within the configured size limit. Expect warnings above ~1 MB and worker-based processing for heavier work. Very large documents can exhaust browser memory.
Is browser-based JSON formatting private?
Yes for this tool: processing stays on-device. Still avoid saving secrets on shared computers, and remember session drafts live in sessionStorage until the tab session ends.
How duplicate JSON keys behave
The JSON grammar does not usefully define duplicates. Most engines keep the last value. This tool warns when it detects duplicates so you can fix the source document.
Why comments are not valid JSON
JSON is a data interchange format, not a programming language. Comments were intentionally excluded. Use JSONC only when both producer and consumer explicitly agree.
FAQ
JSON formatter FAQs
Straight answers about formatting, validation, privacy, repair, tree view, and file handling.
What is a JSON formatter?
A JSON formatter pretty-prints JSON with consistent indentation so nested objects and arrays are easier to read. The Web6 tool also validates, minifies, compares, and inspects JSON in your browser.
Is this JSON formatter free?
Yes. The Web6 JSON Formatter is free to use with no account and no server-side processing of your JSON content.
Is my JSON uploaded to Web6?
No. JSON is processed in your browser. Web6 servers do not receive your JSON content for formatting, validation, or storage.
Can I validate JSON?
Yes. Validate mode checks standard JSON syntax and reports whether the document is valid.
Does it show the error line and column?
Yes. Invalid JSON shows an error message with line, column, character index, a snippet, and an explanation when possible.
Can I minify JSON?
Yes. Minify removes unnecessary whitespace while preserving values and structure. Size savings are plain-text only, not gzip or Brotli.
Can I beautify JSON?
Yes. Format / Beautify mode pretty-prints valid JSON using 2 spaces, 4 spaces, or tabs.
Can I compare two JSON files?
Yes. Compare mode runs a structural diff with added, removed, changed, and type-changed paths. You can ignore key order; ignoring array order is optional and off by default.
Can I view JSON as a tree?
Yes. Tree view expands objects and arrays, shows types and counts, and lets you copy JavaScript paths, JSONPath, JSON Pointer, values, and node JSON.
Can I sort JSON keys?
Yes. Sort keys alphabetically (ascending or descending), case-sensitive or insensitive, recursively or top-level only, with optional natural numeric sort. Arrays are never reordered.
Can I upload a JSON file?
Yes. Drag and drop or choose a .json / text file. The file is read locally in your browser and is not uploaded to Web6.
What is the maximum file size?
The default limit is 10 MB and is configurable in settings. Larger documents may use significant browser memory and are processed with workers when possible.
Can I download formatted JSON?
Yes. Download formatted, minified, sorted, or repaired JSON, plus diff and stats text reports.
Can I escape JSON?
Yes. Escape modes include JSON string escaping, JavaScript string literals, single-line escaped values, and optional Unicode escaping.
Can I unescape JSON?
Yes. Unescape mode converts JSON string escape sequences back to plain text when the input is valid.
Can it repair invalid JSON?
Only with an explicit Safe Repair action. It attempts low-risk fixes such as trailing commas, comments, bare keys, and clear single quotes. It never runs automatically and may not fix every document.
Are comments valid in JSON?
No. Standard JSON does not allow // or /* */ comments. Safe Repair can strip them if you request it.
Are trailing commas valid in JSON?
No. Trailing commas before } or ] are invalid in standard JSON.
Can JSON use single quotes?
No. JSON requires double quotes for strings and property names.
What happens with duplicate keys?
Many parsers keep only the last value for a duplicate key. This tool warns when duplicate keys are detected in the same object.
Can I save snippets locally?
Yes, when you explicitly save. Up to 20 snippets stay in localStorage on this device only.
What happens if I clear browser storage?
Drafts, preferences, and saved snippets stored for this tool are removed from that browser.
Can I use it on mobile?
Yes. Mobile layouts use Input, Output, Tree, and Errors panes for the main workspace.
Does it support large JSON files?
Yes within the configured size limit. Files over about 1 MB use warnings and Web Workers when available. Unlimited sizes are not promised.
Does it execute JSON content?
No. JSON is parsed and rendered as text only. Nothing is executed.
Can it validate JSON Schema?
Not in version 1. This tool validates JSON syntax, not JSON Schema documents.
What is the difference between JSON and JavaScript objects?
JSON is a data format with strict syntax: double quotes, no functions, no comments, no trailing commas. JavaScript object literals are more permissive.
Can I copy a JSON path?
Yes. Tree view and search results offer JavaScript-style paths, JSONPath-style paths, and JSON Pointers.
Can I compare arrays?
Yes. By default arrays are compared by index. Optional ignore-array-order mode is available and clearly labeled.
How do I clear saved JSON data?
Use Clear all data in Saved snippets, or clear site data in your browser. This removes preferences, drafts, and snippets for the tool.
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This tool processes JSON locally in your browser. Avoid storing secrets, tokens, passwords, personal data, or confidential API responses on shared devices.
Safe Repair can correct only selected syntax patterns and may change malformed input. Always review repaired output before using it. This tool does not validate JSON Schema and does not execute JSON content.