JSON Formatter

JSON Formatter takes a JSON document — however badly it has been squeezed onto one line — and rewrites it with two-space indentation and a line break per key, so the structure becomes visible instead of implied. Nested objects and arrays are indented by depth, which is usually all it takes to spot a missing bracket or a value that landed in the wrong object.

It doubles as a validity check. Parsing happens before formatting, so anything that is not well-formed JSON is rejected with the parser's own message rather than being reformatted into something that looks plausible. That distinction matters: a formatter that silently "fixes" malformed input hides the error you were trying to find.

The output preserves key order exactly as it appeared in the input — nothing is sorted or normalised. That is deliberate. When you are comparing two API responses to find what changed, reordering the keys would defeat the entire exercise.

The indent width is part of the page rather than a setting, so a house style that calls for tabs, four spaces or a different bracket placement cannot be reproduced here — a separate indent tool exists for the common alternative width. Comments are not tolerated anywhere in the document: JSON has no comment syntax, so a block preceded by // or wrapped in /* */ is a parse error and the formatter will not strip it for you. Duplicate keys are not collapsed or flagged either; the parser keeps the last occurrence and the earlier one vanishes without comment. Nor does the page validate against a schema, so well-formed JSON that violates the shape your API expects will format cleanly and look entirely correct.