JSON Pretty Formatter
Unreadable JSON from an API response, a log line or a config file becomes legible in one step: the tool reads your input with your own browser’s JSON parser and writes it back with two spaces of indentation per level. If the input is invalid you get that same parser’s error message, including the position where it gave up, which is usually enough to spot a missing comma or a stray brace. Because it is the built-in parser, exactly the same rules apply as in your code: no comments, keys in double quotes, and no trailing comma after the last element. Everything happens locally in your browser. Your JSON never reaches our server, is never logged and never stored — so you can safely paste a response containing real customer data. Use is free and unlimited, including commercially: no account, no licence, no cap on how often or how large.
What people use this for
{"name":"Mira","roles":["assistant","analyst"],"active":true}Returned indented with two spaces per levelInvalid input → message with the position where parsing failed
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Why is my JSON rejected when it looks fine?
It is usually one of four things. A comma after the last element of an object or array (a trailing comma) is allowed in JavaScript but not in JSON. Keys must be wrapped in double quotes — single quotes or no quotes at all is invalid, even though Python and JavaScript accept it. Comments do not exist in JSON: no // and no /* */. And finally, bare values such as NaN, Infinity or undefined are not valid JSON. The error message names the position where the parser stopped; the problem is almost always just before it.
Is the order of my keys preserved?
Yes, for ordinary keys the order stays exactly as you entered it. The JSON specification does not guarantee this — an object is formally an unordered collection — but in practice every browser preserves insertion order. One exception: keys that look like integers (for example "1" or "42") are always sorted numerically and placed before the other keys by JavaScript. That is behaviour of the language itself, not of this tool, and you will see it in any JavaScript environment.
Can I paste sensitive data here?
Processing happens entirely in your browser: not a single character of your input goes to our server, nothing is logged and nothing is stored. Close the page and it is gone. Do bear in mind that until then the text simply sits in your browser — on a shared or managed machine that is a consideration, as it is with any other tab. To verify it yourself: open the network tab of your developer tools and you will see that formatting triggers no request at all.
Is there a limit on how much JSON I can paste?
We impose none. The only ceiling is your own browser’s working memory, which in practice sits at a few megabytes of text before things get noticeably slow. If a very large file stalls, that is your browser and not our server — cutting out a section and formatting that will work. There is no daily cap, no rate limit and no paid tier with a higher allowance.
How is this different from validating JSON against a schema?
This tool checks syntax: is this valid JSON? It says nothing about the content. A JSON Schema validator goes a step further and checks whether the structure matches what you expect — whether "age" is a number, whether "email" is required, whether an array holds at least one element. For that you need a schema you define yourself. Syntax checking is always the first step: if the JSON does not parse, a schema validator will not get through it either.