Using JavaScript object syntax
JSON is stricter than JavaScript object literals: use double-quoted keys, no comments, and no trailing commas.
JSON Formatter | Beautify or Minify Exact JSON Text
FormattingRuns in Your Browser (No Uploads)
Beautify or minify strict JSON without reserializing number spellings or silently dropping duplicate keys. Choose 0 to 10 spaces, inspect exact line and column errors, copy or download the result, and keep processing inside the browser.
What to do next
Continue with a related workflow or open the next tool that usually follows this task.
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OpenHow to Use This Tool
Choose Format for readable indentation or Minify for compact structural whitespace.
Load the strict JSON document you want to indent or compact; the editor accepts one root and at most 10,000,000 UTF-8 bytes.
Use Live mode for immediate processing or Manual mode to avoid repeated work while editing a large document.
Select 2 or 4 spaces, or a custom indentation from 0 through 10, then review exact syntax and duplicate-key diagnostics.
Compare the result, copy or download the exact output, and validate schema or business rules separately before use.
When to Use This Tool
Inspect an API response without reserializing it
Pretty-print a compact REST, GraphQL, or webhook body while retaining the exact property and number tokens that were received.
Prepare a configuration file for review
Find a broken comma, quote, escape, or container before a package.json, tsconfig.json, fixture, or application setting reaches CI.
Create an auditable review sample
Make a dense sample readable while preserving duplicate-key evidence for a pull request, incident note, or documentation example.
Create a compact exact-text fixture
Remove only structural whitespace before placing a verified fixture or non-secret payload into a constrained text field.
Common Mistakes
Validating only after deployment
Paste configuration or API samples here before shipping so syntax errors are caught with line and column details.
Minifying before debugging
Beautify unfamiliar data before review; minify only when you need a compact payload for transport or storage.
Treating duplicate keys as harmless
Duplicate keys are preserved so the formatter does not hide the source problem, but downstream parsers may keep different values. Resolve every reported duplicate path before using the document.
Equating local processing with data authorization
Local browser processing prevents this tool from intentionally uploading the input. It does not grant permission to paste production tokens, personal records, or customer payloads into an unapproved device or browser session.
Examples
Pretty-print an API response
A compact API response becomes readable, indented JSON that is easier to inspect during debugging or review.
Input
{"user":{"id":42,"roles":["admin","editor"]},"active":true,"lastLogin":"2026-05-13T09:30:00Z"}Output
{
"user": {
"id": 42,
"roles": [
"admin",
"editor"
]
},
"active": true,
"lastLogin": "2026-05-13T09:30:00Z"
}Minify a configuration object
Indented configuration JSON can be minified before embedding it in test fixtures, docs, or payload examples.
Input
{
"feature": "search",
"enabled": true,
"limits": {
"pageSize": 50,
"timeoutMs": 3000
}
}Output
{"feature":"search","enabled":true,"limits":{"pageSize":50,"timeoutMs":3000}}Expose a duplicate key without discarding it
The formatter preserves both duplicate properties and reports their exact paths instead of parsing and silently keeping only the last value.
Input
{"role":"viewer","role":"admin"}Output
{
"role": "viewer",
"role": "admin"
}Preserve number lexemes and string identifiers
Numeric source text remains textually stable during whitespace formatting, including exponent notation that a parse-and-serialize formatter might rewrite.
Input
{"threshold":1e+3,"identifier":"00123"}Output
{
"threshold": 1e+3,
"identifier": "00123"
}Token-preserving JSON whitespace edits with bounded strict parsing
The formatter accepts one strict JSON root: an object, array, string, finite number, boolean, or null. Property names and strings require double quotes, while comments, trailing commas, NaN, Infinity, raw control characters, and additional roots stop formatting.
The parser maps failures to one-based line and column positions and distinguishes missing commas or colons, incomplete containers, bad escapes, invalid numbers, trailing content, and other common failure classes.
Formatting edits only structural whitespace. It does not rebuild the document from JavaScript values, so duplicate properties and source number lexemes such as 1e+3 remain visible. Duplicate paths are also reported as warnings.
Indentation is bounded from 0 through 10 spaces. Parsing is bounded to 512 nesting levels and 10,000,000 UTF-8 input bytes; documents above 1,000,000 bytes receive a performance warning.
Processing, copying, and file creation stay in the browser. Aggregate analytics may record mode, indentation, byte counts, warnings, duration, and stable error codes, but not input or output text.
Frequently Asked Questions
Does formatting change JSON values or number text?
Formatting changes structural whitespace only. This implementation preserves duplicate properties and original number spellings such as 1e+3 instead of parsing and serializing them into a different document. One leading byte-order mark is removed before output.
Can I use single quotes in JSON?
No. Per RFC 8259, keys and string values must use double quotes (").
Are trailing commas allowed in JSON?
No. Valid JSON does not allow trailing commas after the last item of an array or object.
What is the exact JSON input limit?
The input limit is exactly 10,000,000 UTF-8 bytes, with a warning after 1,000,000 bytes. Manual mode avoids repeated live processing, but it does not raise the limit. Use a streaming or command-line workflow for larger documents.
Does valid formatted JSON satisfy my API schema?
No. The formatter checks strict RFC 8259 syntax and reports duplicate keys, but it does not verify required fields, application types, value ranges, or business rules. Use JSON Schema or application validation for those contracts.
Is local processing enough for sensitive production JSON?
The source is processed in the current browser and operational analytics omit the input and output. Still redact tokens, personal data, and customer records unless your organization explicitly permits handling them in that browser session.
How This Tool Was Verified
Maintained and tested by SimpleWebUtilsReviewed
Method: To check “API response with nested user data”, we used JSON Formatter with the guide's exact source data and applied “Format without reserializing values”. The output had to match the documented result; evidence for “Formatting logs that include non-JSON prefixes” and “Debugging escaped JSON without decoding it first” was reviewed before recording the check.
Expected result: The minified response formatted into the documented user and meta hierarchy without changing IDs, role order, requestId, or numeric duration.
Sources and standards
Related workflow guides
Use these focused guides when you need a practical workflow before opening the tool.
Workflow guide
Decode a Base64 API payload without corrupting bytes
Use this repeatable workflow for encoded JSON fields, webhook metadata, headers, cookies, and logs. It validates the alphabet and padding before decoding, preserves binary bytes for download, and keeps Base64 separate from encryption or signature verification.
Workflow guideConvert CSV to JSON for spreadsheet data cleanup
Use this workflow when a spreadsheet export needs to become API-ready JSON, a fixture, or a reviewable dataset while preserving the text that the sheet actually contains.
Workflow guideFix CSV and JSON conversion errors
Use this workflow when a spreadsheet export, API fixture, or CSV/JSON handoff fails because columns shift, headers disappear, characters look broken, or JSON will not parse.
Workflow guideConvert CSV or JSON to a Markdown table without corrupting data
A documentation table is reliable only when its source shape, conversion rules, and published rendering agree. This workflow starts with a scrubbed representative fixture, distinguishes quoted CSV from strict JSON object arrays, protects large numbers and nested values, checks every generated header and padded cell, and verifies the finished GFM with the exact renderer that will publish it.
Workflow guideDebug encoded query parameters without double-decoding them
Use this workflow when a callback, search link, webhook, or API request changes plus signs, repeated keys, JSON string escapes, or a nested return URL after more than one parser touches it.
Workflow guideFormat JSON for API debugging
Use this workflow when a compact response is hard to inspect, a fixture fails strict parsing, or a generic client error must be traced to an exact JSON location without confusing syntax with API-contract validity.
Workflow guideHow to extract values from a JSON response with JSONPath
Use this workflow when a response is valid JSON but too large to inspect manually, and you need a focused list of values for debugging, QA, or documentation. Keep the expression beside the extracted result so another person can repeat the selection against a newer response instead of relying on a one-time copy.
Workflow guideDebug API JSON faster with JSONPath expressions
Use this workflow when a bug report, test failure, or production log includes a large JSON payload and you need to isolate request IDs, statuses, pagination links, or nested error fields.
Workflow guideConvert a JSON array to CSV for spreadsheets
Use this workflow when an API response, fixture, or exported JSON array needs to become a spreadsheet-friendly CSV table for review, sorting, filtering, or sharing.
Workflow guideGenerate TypeScript types from an API JSON response
Use this workflow to turn a representative API response into a useful TypeScript starting point without pretending that one payload is the complete contract. It combines strict JSON cleanup, several array samples, explicit inference review, compilation in the target project, and runtime validation at the network boundary.
Workflow guideConvert JSON and YAML configuration files safely
Use this workflow when an API example, application config, or deployment manifest needs to move between JSON and YAML without silently changing a key or numeric value.
Workflow guideGenerate test fixtures without copying production data
Representative fixtures preserve the shape and constraints of production records without preserving real people, identifiers, or secrets. This workflow inventories a target schema, generates only bounded valid values, adds deliberate minimum, maximum, duplicate, empty, and malformed cases, validates the exported encoding in the real importer, and saves stable fixtures when tests must be reproducible.
Workflow guideFormat SQL for code review and verify query behavior
SQL formatting can expose joins, predicates, grouping, and subqueries, but readable output is not evidence that a statement is valid or safe. This workflow identifies the target database and version, preserves and redacts the source, applies one explicit formatter grammar, reviews exact token and comment changes, and then verifies schema resolution, permissions, result sets, plans, transactions, migrations, tests, and rollback in the real toolchain.
Workflow guideExtract and convert timestamps from API logs
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Workflow guideBuild a UTC incident timeline from Unix timestamps
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Workflow guideCheck JWT expiration and not-before timestamps
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Workflow guideGenerate UUID v4 fixtures without copying production IDs
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