Question 1

What algorithm is used for the diff?

Accepted Answer

FileMint uses the Longest Common Subsequence (LCS) algorithm on the pretty-printed lines of both JSON documents. This is the same technique used by git diff and similar tools, producing a minimal set of changes.

Question 2

Does the order of keys matter?

Accepted Answer

Yes — the diff is line-based after pretty-printing. If both JSONs are semantically equal but key order differs, the diff will show changes. For a semantic comparison ignoring key order, we recommend sorting your keys first in the JSON Formatter.

Question 3

Can I diff large JSON files?

Accepted Answer

Yes, up to the limits of your browser's memory. The LCS algorithm uses O(m×n) space where m and n are the number of lines. For very large documents (thousands of lines), diffing may take a few seconds.

Question 4

What if one of my JSON inputs is invalid?

Accepted Answer

The tool validates both inputs before starting the diff. If either is invalid JSON, you'll get a clear error message pointing to which panel has the issue and showing the parser's error description.

Question 5

How is this different from the JSON Formatter?

Accepted Answer

The JSON Formatter beautifies a single JSON document. JSON Diff compares two documents and shows you what changed between them. Use the Formatter first if you want to normalize both inputs before comparing.

JSON Diff

What is JSON Diff Checker?