JSON Formatter

What the indent menu actually passes

The select is shown only in Format mode. Its options are 2 spaces with value 2, 4 spaces with value 4, and a third option whose visible label is 1 tab (\t) and whose value is the number 1. JSON.stringify treats a numeric space argument as that many space characters, capped by the engine at ten. The third option therefore indents with one space. It does not insert a tab, despite the label. Four spaces produce a wider block of the same object. Minify hides the select and passes no space argument, so the sample object becomes {"title":"Toolbench","status":"ready"} with no gap after the colon or the comma.

Run is required after every change. Picking 4 spaces, or pressing Minify, leaves the previous panel in place until the click. A successful click replaces the panel and publishes that string to Copy output. Before the first success, Copy output has nothing stored.

What JSON.parse accepts

The parser accepts objects, arrays, strings, numbers, true, false, and null. It accepts leading whitespace. It rejects comments, single-quoted strings, and trailing commas. A failure clears the panel to empty and sets the status to Invalid JSON: followed by the parser's own message, including a position when the engine provides one. The previous pretty text does not stay on screen after a failure.

Duplicate keys keep the last value, which is ordinary JSON.parse behavior. Key order in the output is the order the parser recorded. Numbers stay IEEE-754 values, so a very large integer can change when it is parsed and written back. The page does not preserve the original spacing, and it does not sort keys. undefined cannot appear in the input because it is not JSON.

Jobs before a conversion or a diff

A minified API body is hard to split by eye. Format it here, then copy the array or object you actually need. The guide Convert nested JSON to CSV without losing fields starts from a JSON array of records. Pretty-printing does not flatten nested objects. That conversion is a separate step on JSON to CSV. Two payloads that should be compared belong on JSON compare, which diffs structure rather than indent.

YAML documents are not parsed here. If the source is YAML, convert it on the YAML ↔ JSON converter first. That converter's JSON output is already two-space indented. You would use this formatter afterward only to switch to four spaces or to minify. This page will not drop YAML comments, because it never sees them. It also will not repair a file that is almost JSON.

Empty input, minify, and the tab label

An empty field fails JSON.parse. The status is the Invalid JSON prefix plus the engine message, and the result is cleared. The word null, the word true, and a bare number are legal JSON and will format. An empty object formats as {} even in Format mode, because there is nothing to indent. An empty array formats as [].

Do not expect the third menu entry to emit a tab character. If you copy the one-space result into a file, the indent bytes are U+0020. If you need a tab, this control will not produce one. Minify is the opposite extreme: one line, no added spaces, still valid JSON. There is no download button beside Copy output.

Rules and limitations

Format calls JSON.stringify with 2, 4, or 1. The value 1 is one space, even though the option label says tab. Minify calls JSON.stringify with no space argument. Both paths require the text to parse.

Comments, trailing commas, and single quotes fail and clear the result. Mode and indent changes apply on the next Run. There is no download, no key sort, and no YAML parser.

Common problems

If the indent looks like a single space, the menu is on the option labeled 1 tab (\t). Choose 2 spaces or 4 spaces and press Run again.

If the panel goes blank, the status begins with Invalid JSON:. The previous format is not kept. Fix the text and press Run.

Frequently asked questions

About this tool

Maintained by Toolbench. For large or deeply nested files, split the input into smaller batches and verify representative results before using them in an import or application. Report reproducible problems through Contact.