JSON Formatter & Validator
Prettify, minify, sort keys and validate JSON — entirely in your browser. Your payloads never leave the page.
- Runs in your browser
- No upload, no tracking
- Free forever
How it works
A JSON formatter takes raw, escaped or minified JSON and rewrites it with consistent indentation so it is readable and diff-friendly — while validating that the syntax is correct. This tool runs entirely client-side, so even sensitive payloads stay on your machine. It is built by JusDB, a managed database operations team, for the JSON work that surrounds every database: inspecting API responses, config and query results.
- 1
Paste your JSON
Drop any JSON string into the input panel — an object, an array, or an escaped blob.
- 2
Choose an action
Format to beautify with 2-space indentation, Minify to collapse to one line, or Sort keys to order alphabetically.
- 3
Fix any errors
Invalid JSON is flagged with the exact line and column of the first problem so you can correct it fast.
- 4
Copy the result
Copy the formatted output to your clipboard with one click. Nothing is ever uploaded.
Frequently asked questions
- Is my JSON data safe?
- Yes. All formatting, minifying and validation happens locally in your browser using JavaScript. Your JSON is never uploaded to JusDB or any server, so it is safe to paste production payloads, secrets and PII.
- What does the JSON formatter do?
- It re-indents raw or minified JSON for readability, minifies it to a single line, optionally sorts object keys alphabetically, and validates the syntax — reporting the exact line and column of the first error.
- Can it handle large JSON files?
- Yes. It uses the browser's native JSON parser, which handles multi-megabyte objects efficiently without sending anything off your machine. Very large inputs are limited only by your browser's available memory.
- Why does it say my JSON is invalid?
- The native parser is strict — trailing commas, single quotes, unquoted keys and comments are not valid JSON. The error message shows the position of the first problem so you can fix it. JSON5 and JSONC are not supported.
- What is the difference between formatting and minifying?
- Formatting (beautifying) adds indentation and line breaks so JSON is easy to read and diff. Minifying strips all whitespace to produce the smallest valid payload, which is ideal for API responses and config you want to ship.
When a JSON formatter actually earns its keep
Most JSON work is not about pretty-printing for its own sake — it is about making a malformed or unreadable payload tell you what is wrong. The scenarios below are where re-indenting, sorting and strict validation save real debugging time.
Debugging API responses and logs
A failing request usually returns JSON collapsed onto a single line, often double-escaped because it travelled inside another string field. Formatting it reveals the structure: which key is null, where the error object actually sits, and whether the server returned an HTML error page instead of JSON at all (the validator will flag a leading < immediately).
Structured logs are the same problem at scale. Pasting one log line and beautifying it turns a 400-character blob into a readable tree, so you can spot the offending field without scrolling sideways through your terminal.
The pitfalls strict JSON will reject
JSON is far stricter than the JavaScript object literals it resembles. Trailing commas, single-quoted strings, unquoted keys, comments, and bare NaN or Infinity values are all invalid — even though many editors and configs accept them as JSON5 or JSONC. If a payload only parses elsewhere, one of these is usually why.
The quieter trap is precision. JSON has a single number type, and parsers coerce it to a 64-bit float, so an integer ID like 9007199254740993 silently loses its last digits. When a backend sends 64-bit IDs or high-precision decimals, transport them as strings. Duplicate keys are another silent hazard: they are technically legal, but parsers keep only the last occurrence, so a config can behave differently from how it reads.
Format, minify, or sort keys — picking the right one
Format when you are reading or hand-editing. Minify when you are shipping: API responses, embedded config and cache values all benefit from dropping whitespace, and the payload stays byte-for-byte identical in meaning. Sort keys when you need a stable, deterministic ordering.
Sorting is the underrated one. JSON objects have no inherent key order, so two semantically identical objects can produce a noisy git diff purely because keys moved. Sorting both sides before comparing — or before committing a generated config — makes diffs reflect real changes only.
JSON and your database
JSON rarely stops at the API boundary. In PostgreSQL, a jsonb column normalises and reorders keys on write and discards duplicates, so what you store is not always the literal text you sent — validating before insert avoids surprises in later -> path queries.
Document stores like MongoDB are more permissive about shape but still bite on number precision and on extended types such as $date. Formatting an exported document first makes its nesting obvious before you write a query against it.
Working with nested or escaped payloads constantly? Validate first, then sort keys before diffing or storing — it eliminates whole classes of phantom changes and precision bugs before they reach your database.