Format, prettify, or minify JSON instantly. Validate syntax, detect errors, copy results, and download clean JSON files with a fast and simple interface.
Developers reach for a JSON formatter when API responses, config files, or log outputs arrive as a single compressed line. Minified JSON strips all whitespace and line breaks to reduce payload size, which is great for servers but unreadable for debugging.
This tool restores indentation (your choice of 2 or 4 spaces), nests arrays and objects correctly, and flags anything that doesn't meet the JSON specification (RFC 8259) so you know immediately if something is wrong. It runs entirely in your browser using JSON.parse and JSON.stringify - your JSON never leaves your device, which matters when the payload contains API keys or private data.
If a field inside your JSON is itself a JWT or Base64 string, decode that field first with the Text Encoder & Decoder, then format the result here.
Paste JSON you already have - a minified API response, a config blob, a log line - and get it readable, validated, or minified again without opening a full IDE.
Paste your raw or unformatted JSON into the input area.
Beautify JSON for readability or minify it for production use.
Instantly detect syntax errors and invalid JSON structures.
Copy formatted JSON to clipboard or download it as a .json file.
Debug REST API responses copied from Postman or browser DevTools.
Validate configuration files for Node.js or Python projects.
Review JSON exports from a database.
Check webhook payloads before wiring up a handler.
Read the JSON payload returned by an AI assistant's tool call.
Format JSON before pasting it into documentation.
Confirm a JSON string is well-formed before you try to parse it in code.
Export the cleaned-up records to a spreadsheet with the JSON to CSV Converter.
Best For
Raw JSON
{"user":{"name":"Aisha","active":true},"role":"admin"}Formatted JSON
{
"user": {
"name": "Aisha",
"active": true
},
"role": "admin"
}Click Minify to collapse the output straight back to that single-line form - the data never changes, only the whitespace.
Broken Input
{"a":1,"b":2,}Validation Result
Invalid JSON syntaxNote the comma after 2 - JavaScript allows a trailing comma in an object literal, but the JSON spec does not, which makes this one of the most common copy-paste errors from browser DevTools or a JS config file.
Copy a minified response body from Postman or your browser's DevTools Network tab and format it to read the structure at a glance.
Paste a JSON config file to confirm it parses correctly - catching a syntax error here is faster than finding it after a failed deploy.
Format the JSON arguments an LLM tool call returns to check the structure matches what your handler expects.
Strip whitespace from a formatted JSON file to reduce its size before storing it or sending it over a network.
Problem
Solution
A comma after the last item in an object or array - {"a":1,} - is valid in a JavaScript object literal but invalid in JSON. Remove the trailing comma.
Problem
Solution
JSON strings and keys must use double quotes. {'a': 1} fails to parse; {"a": 1} works.
Problem
Solution
{a: 1} is valid JavaScript but invalid JSON - keys must be quoted strings: {"a": 1}.
Problem
Solution
JSON has no comment syntax, not // and not /* */. Some config formats (JSONC, used by some editors) allow comments, but this formatter - like the browser's native JSON.parse - does not.
2-space indentation keeps flat objects compact, but a deeply nested API response can be easier to scan with 4-space indentation since each level is more visually distinct.
If you're pasting several versions of a payload while debugging, enable Auto Format so each paste formats immediately instead of clicking Format every time.
Whitespace differences make two otherwise-identical payloads look different in a diff tool - minify both first so you're comparing only the actual data.
The formatter reports that JSON is invalid; it doesn't guess at the intended structure and repair it for you. Fix the syntax error yourself, then format again.
Only standard JSON (RFC 8259) is accepted. Comments and trailing commas, which JSON5/JSONC allow, are flagged as invalid here.
The error message confirms the JSON is invalid but doesn't point to a specific line or character - for a large payload, you may need to check it in sections to isolate the problem.
JSON is a stricter subset of JavaScript object syntax - a JavaScript object literal permits things JSON doesn't, but JSON.stringify() output always follows JSON's stricter rules.
| JSON | JavaScript object | |
|---|---|---|
| Keys | Must be double-quoted strings | Can be unquoted identifiers |
| Trailing commas | Not allowed | Allowed |
| undefined, functions, NaN as values | Not allowed | Allowed |
Which should you use?
Write JS object literals in your code; once that data needs to be serialized - an API response, a config file, JSON.stringify() output - it has to follow JSON's rules, which is what this formatter checks.
Both preserve the exact same data - only the text representation changes.
| Format | Minify | |
|---|---|---|
| What it does | Adds whitespace and indentation | Strips whitespace back out |
| Best for | Reading nested structure | Storage or network transfer |
| Changes the underlying data? | No | No |
Which should you use?
Format while you're reading or debugging the structure; minify right before storing or transmitting it - as shown above, neither changes the underlying data.
The most common question is why JSON that looks fine still fails to parse. A handful of syntax rules trip up almost everyone at some point - see the FAQ below for the exact causes and how JSON's rules differ from a plain JavaScript object.
The most common causes are: a trailing comma after the last item in an array or object (valid in JavaScript but not in JSON), single quotes instead of double quotes around strings, an unquoted key name, or a comment inside the JSON (JSON doesn't support comments - not even // or /* */). The formatter flags the JSON as invalid the moment any of these appear, so if formatting fails, check these four causes first.
JSON is a text format derived from JavaScript syntax, but it has stricter rules. All keys must be double-quoted strings. Values cannot be undefined, functions, or NaN. Trailing commas are not allowed. A JavaScript object literal is more permissive - but when you serialize it with JSON.stringify(), the output must be valid JSON.
Paste the minified JSON into the input field and click Format, or turn on Auto Format to beautify it the moment you paste. The formatter applies consistent indentation (2 or 4 spaces, your choice) and line breaks so nested objects and arrays are readable. This is useful for inspecting API responses, compressed config files, or database query results.
Minifying removes all whitespace, newlines, and indentation from a JSON string. The result is the smallest possible representation of the same data - useful for storing in a database, sending over a network, or comparing against another payload byte-for-byte.
The formatting and validation happen entirely in your browser using the standard JSON.parse and JSON.stringify functions - nothing is uploaded to a server. You can confirm this yourself: open your browser's DevTools Network tab before pasting, and you'll see no outgoing requests fire when you format or validate JSON on this page.
Only whitespace - the data itself is untouched. For example, {"name":"Aisha","active":true,"tags":["admin","dev"]} becomes the same object spread across multiple lines with your chosen indentation (2 or 4 spaces), making the nesting visible at a glance. Minify does the reverse: it strips the formatting back down to that single compact line.
No. This tool parses with the browser's native JSON.parse, which only accepts standard JSON as defined in RFC 8259 - no comments, no trailing commas, and no unquoted keys. Config files like tsconfig.json often use JSONC and will show as invalid here until comments and trailing commas are removed.
There's no hard-coded size limit in the tool itself. Parsing and formatting both happen in your browser's memory, so in practice the ceiling is your device's available memory rather than a fixed number - typical API responses and config files up to several megabytes format instantly.
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