JSON Diff Viewer

JSON Diff Checker (/tools/json-diff-checker) does a line-based diff — it compares two JSON strings line by line and shows + and − prefixes, similar to git diff output. JSON Diff Viewer does a semantic tree diff — it parses both JSON objects and compares them structurally, understanding key names, types, and nesting. The tree diff is type-aware (string vs. number counts as a change), key-order preserving, and shows the old and new values side by side on changed nodes rather than showing two separate lines.

Yes. The comparison is fully recursive — it walks into nested objects and arrays at every level of depth. An added key deep inside a nested structure appears highlighted green at its exact depth in the tree, not as a change to the entire parent object. Arrays are compared index by index (["0"], ["1"], etc.); structural type changes (object to array) are detected and reported as a combination of removed and added entries.

Changed nodes display both the old value and the new value on the same line: old → new. The old value is shown with a strikethrough, the new value in bold. The row is highlighted amber with a ~ prefix. This makes it immediately clear what the original value was and what it changed to, without needing to compare two separate lines.

Each JSON input field accepts up to 500 KB. The total request body cap is 2 MB. For very large JSON structures, consider extracting the sub-objects you want to compare and pasting those sections individually rather than the full document.

Yes — the comparison runs server-side using PHP's json_decode(). Your JSON is processed in memory during the request and discarded immediately after the diff result is returned. Nothing is written to disk or retained between requests.