Diff checker: compare two texts privately in your browser
What a diff checker shows, when developers use one, and how AyeTab Text Diff keeps your input on your machine.
By ClaudeGPT Si Newsroom, Editorial team
3 min read
A diff checker takes two versions of some text and marks what changed between them: lines that were added, lines that were removed, and lines that stayed the same. If you want one that runs in your browser without uploading anything, AyeTab's Text Diff is free, needs no account and keeps your input on your own machine.
What a diff checker does
Reading two long blocks of text side by side and spotting the one changed value is slow and easy to get wrong. A diff tool does the matching for you. It lines up the parts the two versions share, then flags whatever sits outside that shared core. Removed lines usually show in red with a minus sign, and new lines show in green with a plus sign.
Developers reach for one in a few common moments:
- An API response looks wrong and you want to see how it differs from yesterday's.
- Two config files should match across environments, but one service behaves differently.
- A teammate pasted a "small fix" and you want to know what else moved.
- You copied a SQL query or a log line and edited it, and now need to know what you touched.
How to use AyeTab Text Diff
The tool page has two boxes, Original and Modified, each with line numbers. Paste the older version on the left and the newer one on the right. The result appears below as a unified diff, the same single-column format you see in git diff and most code review screens.
| Step | What you do | What you see |
|---|---|---|
| 1 | Paste the first version into Original | Numbered lines |
| 2 | Paste the second version into Modified | Numbered lines |
| 3 | Read the Unified Diff panel | Added and removed lines highlighted |
| 4 | Copy what you need | Nothing was sent anywhere |
Because everything runs locally, the page keeps working after it loads even if your connection drops.
Why local matters for a diff
The text people compare is often the text they should be careful with: a production payload, an environment file, a customer record pulled from a support ticket. When a web tool processes that text on its server, a copy has to travel there first. AyeTab's tool pages state that input is not uploaded to AyeTab servers, so the comparison happens inside your browser tab.
That is the main reason to pick it over a random result from a search. The other is speed: there is no signup screen, no watermark and no usage cap in the product.
The extension version
AyeTab is also a free Chrome extension. It turns your new tab page into a set of developer tools, Text Diff among them, and can open the same tools in a side panel next to the page you are reading. Press Ctrl+K (Cmd+K on a Mac) to jump to a tool by name, and star the ones you use most so they stay at the top. If you paste something recognisable, such as a JWT or a JSON blob, smart paste suggests the right tool. You can add AyeTab from the Chrome Web Store or use the web app with no install.
When another tool fits better
A pasted-text diff is the quickest answer for snippets, payloads and single files. For whole folders, three-way merges or files you would rather open from disk, a desktop program such as WinMerge on Windows or Meld on Linux is the better choice, and inside a repository git diff already knows your history.
FAQ
Is there a free diff checker that does not upload my text? Yes. AyeTab Text Diff runs in the browser, needs no account and does not send your input to AyeTab servers.
Can I compare two texts on my phone? The tool page works on desktop and mobile once it has loaded.
What is a unified diff? A single column that lists removed lines with a minus and added lines with a plus, with some unchanged lines around them for context.