JSON Formatter & Validator: format and validate JSON online
Make messy JSON readable in seconds, find syntax errors by line and column, or minify JSON for APIs and config files. Your data stays in your browser, which is ideal for API responses with sensitive content.
- 100% free
- No sign-up
- Your data stays in your browser
- Errors by line & column
Format and validate JSON
Privacy: your files are processed locally in your browser only and are never uploaded.
JSON Formatter: how it works in 3 steps
Paste your JSON
Paste your JSON into the input box or open a .json file.
Format or validate
Click “Format”, “Minify” or “Validate”. Errors are marked by line and column.
Copy or save
Copy the result with one click or download it as a .json file.
What is JSON?
JSON (JavaScript Object Notation) is a text format for structured data. It is used by almost every web API, many configuration files (e.g. package.json, appsettings.json) and NoSQL databases. JSON consists of objects { }, arrays [ ], strings, numbers, true, false and null.
Common JSON errors
- A comma after the last element (
[1, 2, 3,]) - Single instead of double quotes (
'name'instead of"name") - Unquoted keys (
{name: "Max"}) - Comments with
//or/* */(not allowed in JSON) - Unescaped line breaks or backslashes in strings (e.g. Windows paths:
"C:\Temp")
Format or minify?
Format (pretty print) indents the JSON and makes it readable for humans, ideal for debugging. Minify removes all unnecessary spaces and line breaks and makes files and API requests smaller.
JSON Formatter: your benefits
Data stays local
Your JSON is never sent to a server, so it is safe even for tokens, customer data and internal APIs.
Errors by line and column
The validator shows the exact error position and highlights it in the input.
Sort keys
Sort all keys alphabetically, handy for comparing two JSON files.
Copy and download
Copy the result with one click or save it as a file. Shortcut: Ctrl + Enter.
Frequently asked questions about the JSON Formatter tool
Is the JSON formatter free?
Yes, completely free, without sign-up and without limits.
Is my JSON stored or transmitted?
No. Formatting and validation run entirely in your browser. Your data never leaves your device.
Why does the validator complain about a comma?
JSON does not allow a comma after the last element of an object or array. Remove the last comma and the JSON is valid.
Are comments allowed in JSON?
No. Standard JSON does not allow comments. Formats such as JSONC or JSON5 do, but they are not valid JSON.
How large can my JSON file be?
Files of several megabytes are no problem. The only limit is your device’s memory.
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