Diff Checker — Compare Two Texts and Find Differences Online

Paste the original text on the left and the changed text on the right. The differences are highlighted instantly — additions in green, removals in red — using a line-level longest-common-subsequence algorithm so matching lines stay aligned even when blocks move around.

Split view shows the two snippets in parallel columns, which is the easiest way to read prose, contracts or translations. Unified view interleaves additions and removals in a single column with "+" and "-" prefixes — the same format Git uses, which is convenient for code review.

Yes. Toggle "Ignore whitespace" to collapse runs of spaces and tabs before comparing, which hides reformatting noise. Toggle "Ignore case" to lowercase both sides so "Apple" and "apple" are treated as identical. Both toggles can be combined.

The diff runs in your browser, so size is bounded by available memory rather than a fixed limit. Snippets up to a few hundred thousand characters compute instantly; very large files may take a moment, especially with both ignore-whitespace and ignore-case enabled.

Line-level diffs do not detect moves — when a block disappears from one place and reappears elsewhere, both edits are reported separately. That is the same behaviour as Git's default diff, and it keeps the algorithm fast and predictable.

No. Both snippets are diffed locally in your browser. Nothing is stored, nothing is transmitted and nothing is logged, so it is safe to compare confidential contracts, internal source code or unreleased copy.

Yes — this difference checker works on any text, including source code, JSON, CSV, logs and config files. Paste the old and new versions to compare code online line by line and highlight every added, removed or changed line.

Yes — once a diff is showing, click Copy diff (the primary action button, or the same control in the Settings panel) to copy a plain-text version to your clipboard, formatted with a leading + for additions, − for removals, and a blank prefix for unchanged lines. The button briefly shows "Copied!" as confirmation, and the copied text can be pasted straight into a ticket, email or commit message.

Switch to Split view so the two versions read side by side like the original document, then turn on Ignore whitespace so reformatting and line-wrap differences don't clutter the result, and add Ignore case if inconsistent capitalization isn't meaningful to your review. Once the diff looks right, use Copy diff to export just the flagged changes for a reviewer or client.

Yes — each side is capped at 3,000 lines. If either the Original or Changed box goes over that, the tool stops short and shows an 'Input is too large to diff (3,000 line max per side). Compare smaller sections' warning instead of computing a result, which keeps the tab from freezing on the line-by-line comparison algorithm. If you hit this limit, split the document into smaller sections — by chapter, file or section — and diff each piece separately.

Yes. Paste the two JSON documents and the diff highlights added and removed lines. Because comparison is line-based, pretty-print both documents first so each key sits on its own line — otherwise a one-key change inside a single-line blob marks the whole line as changed. The same approach works for YAML, XML and config files.

Open each file in any editor, copy its contents, and paste one side into Original and the other into Changed — the diff runs instantly in your browser with no upload step. That works for source code, CSVs, logs and configs alike. Very large files can exceed the line limit, in which case compare them section by section.

No — Diff Checker runs entirely in your browser, so what you paste never leaves the machine you are on. That matters if you are checking something that contains a token, a key or customer data. Closing the tab is enough to clear it.

The error points at the first position that could not be parsed, which is usually just after the real mistake rather than on it — a missing comma, an unclosed quote or bracket, or a smart quote pasted in from a document instead of a straight one. Check the line above the reported position first.

Diff Checker shows its result on the page. Standard use does not require signup; this workflow does not offer a file download. Published processing allowances and file limits still apply.

No — Diff Checker runs in the browser on desktop and phone. There is nothing to install, no trial to start, and no license to buy before you can see whether it does what you need. Try it on the file you are actually stuck with rather than a sample.