JSON Formatter
Paste raw JSON, fix syntax problems, then switch between readable and compact output without leaving the page. This JSON formatter is built for the day-to-day work that happens around APIs, config files, logging payloads, webhooks, and exported data. If you have a one-line blob from a terminal, a response body copied from DevTools, or a settings object that became unreadable after too many edits, this tool turns it back into structured text you can inspect. It also tells you when the input is not valid JSON, which is usually the real problem. A missing quote, trailing comma, unescaped line break, or stray comment can break an integration fast. Formatting helps you see the shape. Validation helps you trust what you are about to copy into code, a request body, or a deployment config.
Quick answer
Formatting and validation run fully client-side, so your pasted JSON stays in the browser on your own device.
What this tells you
- •Formatting and validation run fully client-side, so your pasted JSON stays in the browser on your own device.
- •Pretty formatting adds indentation and line breaks so nested objects and arrays are easier to scan and debug.
- •Minified output removes unnecessary whitespace, which is useful when you need compact JSON for transport, storage, or embedding.
- •Validation checks JSON syntax, not business rules. A payload can be valid JSON and still be wrong for the API or schema you plan to send it to.
How to Use
- 1Paste JSON into the input area exactly as you received it. That could be an API response, a config object, a webhook sample, or a log payload.
- 2Click Validate & Format first when the structure is hard to read. If the JSON is valid, the output becomes indented and easier to inspect line by line.
- 3Scan the formatted result for the parts you actually care about, such as missing keys, unexpected null values, duplicated fields, or the nesting level of arrays and objects.
- 4If the tool reports an error, go back to the input and look for the usual syntax issues. Common causes are trailing commas, double quotes replaced with single quotes, comments copied from JavaScript, or pasted text that is not wrapped as a string value.
- 5Use Minify when you need the same data in the smallest readable machine format, for example before pasting JSON into an environment variable, request body field, or test fixture.
- 6Copy the output only after you confirm both the syntax and the structure. Formatting can tell you whether JSON parses, but it cannot confirm that an endpoint expects those keys or values.
Worked Examples
Pretty format a one-line API response
The original payload is valid, just cramped. After formatting, you can immediately see the user object, the roles array, and the boolean status without counting braces in a single line.
Catch a trailing comma before sending a request
JSON does not allow a trailing comma after the last property in an object or the last item in an array. This mistake is common when data is copied from JavaScript object literals.
Minify JSON for an environment variable
The data stays the same, but whitespace is removed. That is helpful when a deployment form or secret manager expects compact JSON in a single field.
Common JSON syntax issues
These are the problems people run into most when a payload refuses to parse.
| Issue | Invalid example | What to do instead |
|---|---|---|
| Trailing comma | { "a": 1, } | Remove the comma after the final property |
| Single quotes | { 'a': 1 } | Use double quotes for keys and string values |
| Comments | { "a": 1 // note } | Remove comments because JSON does not support them |
| Unquoted key | { a: 1 } | Wrap the key in double quotes as "a" |
| Raw line break in string | { "msg": "hello\nworld" } | Escape the line break or keep the string on one line |
| Multiple top-level values | {"a":1}{"b":2} | Wrap the values in an array or keep only one top-level object |
JSON is stricter than JavaScript object literal syntax, which is why copied code snippets often fail until cleaned up.
What this JSON formatter helps with and what it does not
A formatter solves a readability problem first. When a payload is compressed into one line, it becomes hard to answer practical questions. Which keys are siblings. Which values sit inside the same object. Whether an array holds strings, numbers, or nested objects. Pretty printing inserts line breaks and consistent indentation so the structure becomes visible. That matters when you are tracing a bug, comparing two responses, or checking whether a field moved after an API change.
Validation solves a different problem. It answers whether the text follows JSON syntax rules closely enough to parse. That means quoted keys, double-quoted strings, matching braces and brackets, commas only between items, and exactly one top-level value. If parsing fails, the tool can help you narrow the problem down to syntax, which saves time before you dig into deeper application logic.
What it does not do is schema validation or semantic review. A field named `userId` can still be the wrong type. A date string can still use the wrong format. A webhook body can still be missing required keys even if the JSON is perfectly valid. Use this page to clean and inspect the payload first, then validate it against the API contract or JSON Schema your project relies on.
Common mistakes
- Pasting a JavaScript object literal and expecting it to count as JSON. JavaScript allows comments, single quotes in many codebases, and sometimes unquoted keys. JSON does not.
- Assuming valid syntax means correct data. A payload can parse cleanly and still fail because a required field is missing, a number is stored as a string, or the endpoint expects a different nesting shape.
- Editing minified JSON directly when you are troubleshooting. Format first, make the change in the readable version, then minify only if you still need compact output afterward.
- Forgetting that duplicate keys are a logic smell. Many parsers accept them and keep only the last value, which can hide mistakes in hand-edited payloads.
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