How to compare two texts for differences, from prompts to model answers

To compare two texts for differences, paste one version into a diff tool, paste the other beside it, and read the highlighted lines: removals on one side, additions on the other. AyeTab's free Text Diff does this inside your browser without uploading either text, which matters when one of those texts is an unreleased prompt, a draft or a model output with customer data in it.

Why AI work creates so many near-duplicate texts

Working with language models produces versions constantly. You tweak a system prompt and want to know exactly which sentence changed. You ask two models the same question and want to see where their answers part ways. A coding agent edits a file and you want to check its change before accepting it. In each case the two texts are mostly the same, and the eye is bad at finding the few lines that are not.

A diff tool solves that by aligning the shared lines and marking the rest. It does not judge which version is better; it only shows you what moved, so your review time goes to the parts that changed.

Step by step with AyeTab Text Diff

1. Open Text Diff on AyeTab. It loads as a web page; there is nothing to install and no account to make.
2. Paste the older text into the Original box. Line numbers appear on the left.
3. Paste the newer text into the Modified box.
4. Read the Unified Diff panel below. Added and removed lines are highlighted.
5. Copy what you need. The text stayed in your browser the whole time.

A tip for prose: diffs work line by line, so put each sentence or paragraph on its own line before you paste. Two long paragraphs that differ by one word will otherwise show as one big changed line.

Where this helps in an AI workflow

For agent edits inside a repository, git diff already shows the change against your last commit. Outside a repository, git diff --no-index compares any two files, and VS Code opens a side-by-side view with code --diff. A browser tool is quicker when the text is on your clipboard rather than in a file.

Keep private text private

Prompts and model outputs often carry things you would rather not share: internal instructions, customer names, API keys left in a log. Any online tool that processes text on a server needs a copy of it first. AyeTab's tool pages say input is not uploaded to AyeTab servers; the comparison runs in your tab and keeps working offline once the page has loaded.

AyeTab also ships as a free Chrome extension that puts the same tools on your new tab page and in a side panel, with a Ctrl+K command palette to reach Text Diff in a couple of keystrokes. More on the extension at ayetab.com.

When a different tool is the better choice

If you need to compare whole folders, merge three versions, or review documents such as PDFs and spreadsheets, a desktop app like WinMerge or Meld, or Diffchecker's document comparison, will serve you better than a pasted-text diff. For two texts on your clipboard, the browser is enough.

FAQ

How do I compare two texts for differences online for free? Paste both versions into a free browser tool such as AyeTab Text Diff and read the highlighted added and removed lines.

Can a diff tool compare two AI answers? Yes. Put one answer in each box. Split sentences onto separate lines first so the result shows exactly which sentences differ.

Is a diff the same as a plagiarism check? No. A diff shows edits between two versions of one text; it does not search other sources or score similarity.