Compare two texts

Compare an original and revised block of text without uploading drafts, configuration, code, or private notes. FileGizmo performs an ordered line comparison and produces a familiar plain-text result: unchanged lines begin with spaces, added lines with +, and removed lines with -.

The comparison uses a longest-common-subsequence strategy, so matching lines remain aligned even when content is inserted or deleted between them. The summary reports additions and removals separately. A one-million line-pair safety limit prevents accidental browser memory exhaustion; split exceptionally large documents into sections for more focused results.

Everything runs in the current browser page, with no account, stored history, or server transfer. The two source editors remain visible while you review the read-only result. Copy the marked diff into an issue or message, or download it as UTF-8 text. The responsive two-column layout becomes a comfortable vertical comparison on smaller screens.

The comparison is line by line, which suits the documents people actually compare: contracts, configuration files, published copy, and anything that arrives as two versions with no revision history between them. Added lines, removed lines, and unchanged context are marked separately so you can read the shape of the change before reading the change itself.

Line endings are normalised before comparing. A file that has been through Windows and a file that has been through macOS otherwise appear to differ on every single line, which is technically correct and completely useless. Here that difference is ignored, so what you see is the change somebody actually made.

Use it when two people edited the same document without tracked changes, when a page went live and you need to know what moved, or when a configuration stopped working and the only clue is a copy of the version that worked. It answers a narrow question quickly: what is different, and where.

It compares text rather than formatting. Two paragraphs identical in wording but different in font are the same to this tool, and a table pasted from a spreadsheet is compared as the text it becomes. For a Word document with tracked changes, the change history in Word itself is the better instrument.

A line that was edited rather than replaced is now shown word by word. It begins with ~, the words that went are wrapped in [-square brackets-], and the words that arrived are wrapped in {+braces+}, so a changed figure inside a long paragraph is one mark instead of two whole lines to proofread against each other. Lines that were simply added or removed keep the + and - they always had. A pair of lines that are not versions of one another is left alone: marking every word of two unrelated rows as changed is noisier than saying nothing, so the inline view appears only where the two lines are recognisably the same line edited.

Both blocks stay in the page. Nothing is uploaded, which is why this is safe to use on an unsigned contract or an internal draft, the two things people most often want to compare and least often want to paste into a website.